I can't remember my iMac password and I can't reboot
How do I reset my password on an 2010 iMac?
Apple’s Worldwide Developers Conference to kick off June 10 at 10 a.m. PDT with Keynote address
The Keynote will be available to stream on apple.com, the Apple Developer app, the Apple TV app, and the Apple YouTube channel. On-demand playback will be available after the conclusion of the stream.
The Keynote will be available to stream on apple.com, the Apple Developer app, the Apple TV app, and the Apple YouTube channel. On-demand playback will be available after the conclusion of the stream.
How do I reset my password on an 2010 iMac?
Forgot Your Account Password - Change or reset the password of a macOS user account - Apple Support.
Forgot Your Account Password - Change or reset the password of a macOS user account - Apple Support.
I can't get past the login page
Did you actually read the document linked to above?
I can't remember my iMac password and I can't reboot