1.查询提交记录。进入目录，查看某人在此目录下的commit：
panxi@ww-bj-panxi MINGW64 [path]/Business (feature/v2.3) $ git log feature/v2.3 --author=[pan] -- ./
2.根据提交的commit，撤销某次具体的commit（注意切换分支至目标分支）：
git revert 94d26b9c189497c6cda72dffb0c9afee6cb8fb96
3.撤销本地merge（原文链接：Undo a Git merge that hasn't been pushed yet）
With git reflog check which commit is one prior the merge (git reflog will be a better option than git log). Then you can reset it using:
git reset --hard commit_sha
There's also another way:
git reset --hard HEAD~1
It will get you back 1 commit.
Be aware that any modified and uncommitted/unstashed files will be reset to their unmodified state. To keep them either stash changes away or see --merge option below.
As @Velmont suggested below in his answer, in this direct case using:
git reset --hard ORIG_HEAD
might yield better results, as it should preserve your changes. ORIG_HEAD will point to a commit directly before merge has occurred, so you don't have to hunt for it yourself.
A further tip is to use the --merge switch instead of --hard since it doesn't reset files unnecessarily:
git reset --merge ORIG_HEAD
--merge
Resets the index and updates the files in the working tree that are different between <commit> and HEAD, but keeps those which are different between the index and working tree (i.e. which have changes which have not been added).