If you can't enable your migrate module due to already active configuration

This was my error message:

complinetmigration already exists in active configuration

This was the solution:

drush sqlq 'SELECT * FROM config WHERE name LIKE "%complinet%";'
drush sqlq 'DELETE FROM config WHERE name LIKE "%complinet%";'
drush sqlq 'DELETE FROM config WHERE name LIKE "%to_D8%";'

also https://www.drupal.org/project/drupal/issues/2877922

wow, and note to self, my migrations weren't showing up and they previously did, and restarting Acquia dev desktop fixed the problem

also now there's the easy_install module which lets you delete module config data to flush it out.