Malwarebytes for Mac will remove MacKeeper.
1. Use the latest release of Malwarebytes for Mac to remove malware/adware installed on your Mac.
Install guide: https://support.malwarebytes.com/docs/DOC-1817
Uninstall Guide: https://support.malwarebytes.com/docs/DOC-1190
The installer may ask you to allow it in Security & Privacy /System Preference. Allow it.
Click the “Scan Now” button.
Repeat the scan couple of times.
Once done quit Malwarebytes for Mac.
Restart the computer, relaunch Safari holding the shift key down.
2. Additional steps, if necessary.
1. Remove unknown Login item.
System Preferences > Users & Groups > Login items
Authenticate and unlock the lock.
Highlight the unknown login item (Mac Mechanic?) and click the “-“ button at the bottom left to remove it.
2. Remove unknown and third party installed extensions.
https://support.apple.com/guide/safari/use-safari-extensions-sfri32508/mac
3. Reset search engine. https://support.apple.com/guide/safari/customize-your-search-ibrwe75c2a3c/mac
4. Reset Homepage. https://support.apple.com/guide/safari/set-your-homepage-ibrw1020/mac
5. Restart the computer, relaunch Safari holding the shift key down.
6. Remove unknown profiles.
System Preferences > Profiles
Open System Preferences, click the “Profiles” icon ( a checkmark on a gear) .
When Profiles pane opens, select the unknown profile and click the minus button at the bottom.