I am aware that there are similar issues about git relating to the \'unable to unlink\' warning, but I have not been able to use them.
The main difference is that th
You don't have the access permission, maybe because you are not the owner.
Fix by changing the owner to yourself:
sudo chown -R your_login_name /path/to/folder
To those who are using Intellij, as @rtconner said this problem is not caused by git. Since your IDE is locked a file(s) git cannot un-link it. So, you need to close your IDE and then try to merge (or whatever you like) it via command line.