Can I uninstall an update?

LMNobles wrote:

Since installing the Big Sur update last night, my computer has crashed every hour. Am I able to uninstall?

Revert to previous macOS

https://support.apple.com/en-za/guide/mac-help/mh15216/10.15/mac/10.15

How To Downgrade macOS Big Sur To Catalina Or Older ...

https://www.macworld.co.uk/how-to/downgrade-macos-3581872/

Before you downgrade your system you should try to determine what might be causing the problem with Big Sur.

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Additional Text button to include the report in your reply.

➡︎ IMPORTANT: ⬇︎ ⬇︎ ⬇︎

Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:

Also click and read the About info to further permit full disk access.

Then we can examine the report and see if we can determine what might be causing the problem.

Upgrades can't be uninstalled. You can erase and revert to a backup of a prior version with all of your prior data, or erase and install a prior version with the loss of your prior data.

Hence the reason why you should have been maintaining a backup on an external drive.