I don’t remember my iPhone password

If you forgot the passcode on your iPhone, or your iPhone is disabled -

https://support.apple.com/en-us/HT204306

password for what?

If you use Hide My Email.. you can find the email address used in Settings > [your name] > iCloud

If you chose to save your password, you should be able to locate that in Settings > Passwords

If did not chose to save your password, then you will have to go thru the process of resetting your password on the website where you created the account.