how do I unlock my iPhone if I can't remember the password
You don't.
If your iPhone is running iOS 15.2 or higher........(it appears that it might be).......you can use the instructions linked just below which will not require the use of a Mac or PC:
How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support
If you are not sure which operating system is installed on your iPhone, please use the link below, which will require the use of a Mac or PC.
If you forgot your iPhone passcode - Apple Support
If you have a backup of the phone, you can use the backup to restore the data on the phone during the new setup. We'll save the lecture, but backups must occur.....before....trouble strikes. Even if you had room in iCloud, you would not be able to back up the phone in its present state.