If you registered with Google SSO, you can also set up a classic email and password login for the same Trackdesk account.
If you've logged in via Google SSO and haven't set a password yet, your user menu shows Set password instead of Change password:
Click Set password to define one. From then on, you can log in either with Google SSO or with your email and the password you set; both work for the same account.
Once a password has been set, the menu item changes to Change password.
FAQ
I want to change my password for my Trackdesk account, but it's linked to my Google account. How do I unlink?
You don't need to unlink anything. Log in via Google, then use the Set password option in the user menu to set a classic email and password login. From then on, you can log in either way.