IPSW files

IPSW files are software or firmware packages for iPhone, iPad, and Apple silicon Macs, among other Apple products. I would not expect those to be scattered around.

Here is how to un-enroll from the Apple betas: Apple Beta — Unenroll Your Devices

Restore the backup from prior to the installation of the beta.

No backups means no means to revert from a beta, and implicitly means the data involved is not valued. Files and data that were modified by the beta don’t have a mechanism to revert, which makes manually reverting far more effort. It can also mean you’re basically committed to the continuation of the beta, pending the next associated non-beta version of macOS, or an erase-and-install: Erase and reinstall macOS - Apple Support

Do not run a beta on any device you need to work, with any data you need to be available and uncorrupted, with any Apple ID and iCloud account you need available and uncorrupted.

The_iCloudMail_Mysterion wrote:

I did the genious move of backing up my Macbook Air (the one with nothing but usc-c ports for everything) without reading the instructions first when I the beta participations came to play.. So I am blessed now to know everything about ipsw files when I have never envisioned even hearing the word ipsw. The result? I have now everywhere ipsw files, gmail, google drive, probalbly my nan's cupboard...

Is this salvagable or should I just get rid of my laptop?

Is what salvageable? I really have no idea what you are asking.