Best option: Restore an old NAND backup that you should have taken before hacking the system.
Alternate option:
https://3ds.guide/9.2.0-ctrtransfer.html
EDIT: After ctrtransfer, you'll still have A9LH/B9S installed. I believe SafeB9SInstaller can remove B9S. You might have to temporarily upgrade from A9LH to B9S if you have A9LH installed, though.
EDIT 2: After restoring the NAND backup, if you don't want to format the system, you may want to pull the battery to reset the clock. Otherwise, Download Play might show up in the activity log as being used for more than a year straight.