How to return commit code to a state without commit or add

recently I learned git,
I added a line of words to a file 1.txt,
but I was cheap, I changed this to git add,
also carried out git commit operation,

at this point, I want to push, but when I think about it, I feel that I still need some changes. I regret submitting it.

then I checked on the Internet, can git reset-- hard head ^ back and forth a version,
but after I backed back, went back to the previous version, I changed the code is gone.

what I want is to change the status that has just been submitted by commit to the state where there is no commit after git add, or even just change it, without add, or commit.

ask all the bosses to do me a favor. Thank you!

Git
Mar.21,2021

git reset head ^


git reset-- mixed head ^

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3f94a-2b80a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3f94a-2b80a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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