error when trying to modify project in laravel forge

My project is in laravel forge with digitalocean first I added a collaborator and deleted it and since when I try to modify code by git push origin master I receive this error in the dashboard of laravel forge

From github.com:name/project
 * branch            master     -> FETCH_HEAD
   aad781c..e558842  master     -> origin/master
error: Your local changes to the following files would be overwritten by merge:
    public/css/style.css
Please, commit your changes or stash them before you can merge.
Aborting
Updating aad781c..e558842

via Chebli Mohamed