I cant login

You'll need to shut down your Mac. When it's completely off press and hold the power button until you see the gear labeled "options" then click continue.

If you're asked to select an admin user you know the password for, click “Forgot all passwords?”.

Enter your Apple ID information. You might also be asked to enter the verification code sent to your other devices.

If you see an Activation Lock window, click Exit to Recovery Utilities.

If you're asked to select a user that you want to reset the password for:

1. Select the user, then enter your new password information and click Next. 
2. When authentication has succeeded, click Exit. 
3. Choose Apple menu  > Restart. Password reset is now complete, so you don't need to take additional steps.

If that doesn't work click on utilities at the main top, then "terminal", in terminal type this exactly as seen:

resetpassword

Be sure to use no capital letters and no spaced between those words. After typing do not put a space after, just hit return or enter.

1. If you're asked to select an admin user you know the password for, click “Forgot all passwords?”.
2. At the Reset Password window, click Deactivate Mac, then click Deactivate to confirm.
3. If you see an Activation Lock window, enter your Apple ID email and password, then click Next.
4. At the Reset Password window, enter your new password information, then click Next.
5. If this window shows multiple user accounts, click the Set Password button next to each account name, then enter the new password information for each account.
6. When the password reset is completed, click Exit.
7. Choose Apple menu  > Restart, then log in with your new password.

For more information see this article: https://support.apple.com/en-us/HT212190

Good Luck