$ git reset --hard HEAD (going back to HEAD)
$ git reset --hard HEAD^ (going back to the commit before HEAD)
$ git reset --hard HEAD~1 (equivalent to "^")
$ git reset --hard HEAD~2 (going back two commits before HEAD)

git reset --hard origin/main

git reset --hard origin/master
git clean -d --force

$ git reset --hard HEAD (going back to HEAD)
$ git reset --hard HEAD^ (going back to the commit before HEAD)
$ git reset --hard HEAD~1 (equivalent to "^")
$ git reset --hard HEAD~2 (going back two commits before HEAD)

You can restore with this
>> git reflog #Lists the actions, including reference to deleted commit
#You can now find the id of the deleted commit and easily restore it like this
>> git reset (deleted commit id) --hard
#eg. git reset "8c7a2a0" --hard 

git reset --hard f414f31
git reset --soft HEAD@{1}
git commit -m "Reverting to the state of the project at f414f31"

git reset --hard origin/master

git checkout reset HEAD~1

$ git init
Initialized empty Git repository in .git/
$ echo "testing reset" > file1
$ git add file1
$ git commit -m 'added file1'
Created initial commit 1a75c1d: added file1 1 files changed, 1 insertions(+), 0 deletions(-) create mode 100644 file1
$ echo "added new file" > file2
$ git add file2
$ git commit -m 'added file2'
Created commit f6e5064: added file2 1 files changed, 1 insertions(+), 0 deletions(-) create mode 100644 file2
$ git reset --hard HEAD^
HEAD is now at 1a75c1d... added file1
$ cat file2
cat: file2: No such file or directory
$ git reflog
1a75c1d... HEAD@{0}: reset --hard HEAD^: updating HEAD
f6e5064... HEAD@{1}: commit: added file2
$ git reset --hard f6e5064
HEAD is now at f6e5064... added file2
$ cat file2
added new file

#move head back to the specified commit but retain changes made since
#allows to force push to remote if commits were pushed in error
#but work can continue without starting over
git reset abc1234
#move the head back and remove all trace of changes since specified commit
git rset abc1234 --hard
#after either you can force push to the branch so the remote is aware of the rollback
git push -f