Can I just delete my Apple ID?

1.

but I cannot for the life of me remember my security questions, even though I have my username and password correct.

Try this first before you delete your Apple ID.

See this Apple article: If you forgot the answers to your Apple ID security questions

If you forgot the answers to your Apple ID security questions - Apple Support

👉 Scroll to Reset your security questions

1. Go to iforgot.apple.com.
2. Enter your Apple ID, then select Continue.
3. Choose the option to reset your security questions, then select Continue.
4. Enter your Apple ID password, then select Continue. 
5. Follow the onscreen steps to verify your identity. The information you’re asked to provide may vary based on your account details and other factors. If you don't get any options to verify your identity, you can't reset your security questions at this time.
6. Choose new security questions and answers and select Continue. See our tips for choosing security questions and keeping your account secure. 

After you reset your security questions, you might want to set up two-factor authentication instead. It's the best way to keep your account secure, and you won't need to remember any security questions. You can set up two-factor authentication right from your iPhone, iPad, or iPod touch with iOS 9 or later or your Mac with OS X El Capitan or later.

If you answer your security questions incorrectly too many times in a row, you temporarily can't use your security questions. Try to reset your questions after the waiting period ends.

-----

2.

I got an email today saying someone used my apple id to log into an iphone 6 or something.

Looks like spam / phishing.

To keep your Apple ID account secure, see the following Apple articles: 

If you think your Apple ID has been compromised

If you think your Apple ID has been compromised - Apple Support

Recognize and avoid phishing messages, phony support calls, and other scams

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

See who has access to your device or accounts

See who has access to your iPhone or iPad – Apple Support (UK)

Delete suspicious content from your devices

Delete suspicious content from your devices – Apple Support (UK)

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to find where you're signed in - Apple Support

• if you see devices that don't belong to you, delete from your account.

Personal Safety User Guide -> Personal Safety User Guide – Apple Support (UK)

Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)

(if you haven't already done this) Two-factor authentication for Apple ID -> Two-factor authentication for Apple ID - Apple Support

Change your Apple ID password -> Change your Apple ID password - Apple Support

• Create a strong password for your Apple ID, It is best if your password consists of eight or more characters and include upper and lowercase letters, and at least one number. You can also add extra characters and punctuation marks to make your password even stronger. 
• Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else. Apple will never ask you for this information.

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

Never jailbroken your iPhone.

-----

3.

Read carefully what happens if you close and/or delete your Apple ID.

See -> How to delete your Apple ID account

How to delete your Apple ID account – Apple Support (UK)

-> Once your account has been deleted, Apple can't reopen or reactivate your account or restore your data.

See also -> Understand and control the personal information that you store with Apple

Understand and control the personal information that you store with Apple - Apple Support

When you delete your previous Apple ID you get this message:

Your Apple ID has been deleted. This information has been permanently erased from our systems or has been modified so it no longer identifies you.

To delete the account you also have to be able to get access to the account, otherwise Apple doesn't know you are the true owner of the account qualified to request deletion.

Try the directions in the article If you forgot the answers to your Apple ID security questions - Apple Support for resetting your security questions:

"Reset your security questions

1. Go to https://iforgot.apple.com/ .

2. Enter your Apple ID, then select Continue.

3. Choose the option to reset your security questions, then select Continue.

4. Enter your Apple ID password, then select Continue.

5. Follow the onscreen steps to verify your identity. The information you’re asked to provide may vary based on your account details and other factors. If you don't get any options to verify your identity, you can't reset your security questions at this time.

6. Choose new security questions and answers and select Continue."

Note that Apple labeled this article as "archived", which means it has not been updated since December, 2021 and may contain outdated information.

If you get a message about not having 'sufficient information', you will not be able to reset your security questions this way.

The article: About your Apple ID email addresses - Apple Support is updated and it implies you can use a rescue email (if you set one up -- if you did not, it is too late to do that now) to reset your questions: "If you ever forget your security questions, you can use your rescue email address to reset them. We also send any account security-related notifications to your rescue email address." How you do this exactly is not clear and my research into this reveals it may depend upon your region. Here is one possible way (from: https://www.alphr.com/we-do-not-have-sufficient-information-to-reset-your-security-questions/ ) but I have not tested it beyond the first step since I do not want to experiment with my account. ;-).

1. Visit this page and enter your Apple ID -->.https://iforgot.apple.com/password/verify/appleid

2. Enter your rescue email address and have a verification email sent there to reset your password.

3. Follow the link in the email to reset.

If you cannot get any of the above to help with resetting the security questions then realize that several years ago Apple transitioned to using to two factor authentication instead of security questions. Apple has since been persistently encouraging users to switch to the newer security system and your only recourse may now be to try to change to two factor authentication as outlined in this article --> Two-factor authentication for Apple ID - Apple Support Follow the instructions in the section "Turn on two-factor authentication for your Apple ID"

If you can neither reset the questions, nor switch to two-factor authentication, you may well have lost any access to that account.

If you wish to speak with Apple about this, contact with Apple ID account security using the information in this document --> Contact Apple for help with Apple ID account security - Apple Support