Admin API to join user to community

I wants to call API from by backend to join a user to a community - however the API Swagger UI requires an access token which is issued from the user themselves - is there a way for my backend server to just use a single token to allow joining any users to any community?

You can use all the APIs as admin context instead of user context by passing access token issued from ASC Console (super admin will not be able to issue access token)