Downgrade gitlab ee to ce error in removing service integrations


I am very new to gitlab server administration and currently trying to downgrade a gitlab 13.0.5-ee.0 to 13.0.5-ce.0 following below guide.

I Cloned the existing ee server and following above guide on that cloned server.
when I run below command to remove githubservice
sudo gitlab-rails runner "Integration.where(type: ['GithubService']).delete_all"

It gives me below error

Please specify a valid ruby command or the path of a script to run.
Run 'rails runner -h' for help.

uninitialized constant Integration
Did you mean?  Iteration

can anyone help me with this