Please (re)search before posting, there is already another thread about this.
Make sure you have the latest avast version installed.
If you have, it is safe to delete those registry entries.
And no, CCleaner can’t do it as they are still protected by avast.
Manually removing them will work.
Before removing those entries, you need to first uncheck the Avast Self Protection Mode
Avast > Settings > Troubleshooting > Uncheck Avast self defense module.
Now you can remove those entries (manually or via Ccleaner)
Once removed, recheck the Self defense module.