iMac 2015 4k accidently icloud locked from find my

Hi mlnlbrt_,

If we understand correctly, it sounds like you tested locking your Mac using Find My, but you're unable to turn off Find My. Is that right?

If that's correct, this may help you: Activation Lock for Mac - Apple Support

"How to disable Activation Lock

To disable Activation Lock, turn off Find My Mac.

macOS Ventura or later

1. Choose Apple menu  > System Settings.
2. Click your name (Apple ID) in the sidebar.
3. Click iCloud on the right.
4. Click the Show All button on the right, then click Find My Mac and turn it off. Enter your Apple ID password when prompted.

macOS Monterey or earlier

1. Choose Apple menu  > System Preferences.
2. Click Apple ID.
3. Click iCloud in the sidebar.
4. Deselect the Find My Mac checkbox on the right, then enter your Apple ID password when prompted. 

Other ways to disable Activation Lock

• If you don't have access to your Mac or the settings above, use a web browser on another device to remove Activation Lock on the web.
• Activation Lock is disabled when you use the Erase All Content and Settings feature.

If your previously owned Mac shows an Activation Lock window that asks for someone else's Apple ID, the previous owner may need to remove Activation Lock for you."

We hope that helps. If the issue persists, please reply back with more detail about the issue.

Take care.