did you select Security?
The system should allow you to turn it back on.
if it doesn't, then clear the device security data.
follow instructions here: https://www.diytechguides.com/disable-device-security-on-a-samsung-galaxy.html
I think that shortcut was supposed to be removed along with the malware app. I remember on some phones it was and others it wasn't. I can't remember which update removed it. It was either an update for the device care app from the galaxy store or a monthly security update. I would check for both device care updates and system updates.
Galaxy S9 SM-G960U
Android 10 One UI 2.0
Security Patch Level
May 1st, 2020