Reverting a single file in a commit and merge

I made changes to multiple resource files (Excel spreadsheets) in a Java project. I committed the changes and merged the code months back. Now the client wants me to revert the change on a single file but keep the rest. I found instructions on how to do it with the git command line. I was wondering if there was an easier way to do it using the GitLab web site. I could not find an option for it.

I haven’t seen that option either in the Gitlab website, only see an option to revert the whole commit.