How to replace private access token with project access token

Hello,
I need to replace private access tokens with project access tokens in existing projects.
I have created project access token in Gitlab in test project, but I have no idea how to replace user’s credentials (someone who originally added repo) with project token.
When I enter:
git remote add origin https://project_4948_bot:<project_access_token>@git.de/test/test.git
I receive “fatal: remote origin already exists” error
We use Gitlab v14.10.5-ee

Sorry it is problably easy, but I am not very experienced in Git/Gitlab
Your help will be much appreciated!

Greetings,
dzastap