How to restrict access to applications in Big Sur?
I personally don’t recommend blocking things that you as the administrator can unblock, but I understand friction can be good for many people so I would encourage use of screen time - if only to show you the amount of time you spend so you ca track that and build healthy habits over time. Also, it’s quick and easy so start with it while you wait for other answers to arrive.

You can not delete apps in a meaningful way to accomplish your goal in Big Sur. It’s not easy and you have to circumvent the sealed system / patch and update process. Plus you may waste more time than you save in a week, but have at it if someone documents a solution there.
Use Screen Time to block whole apps.
Use the SelfControl app to block sites in Safari (and other browsers) https://github.com/SelfControlApp/selfcontrol/wiki/FAQ

Be sure you read the self control FAQ. It has some amazing gems of wisdom in it. Good luck tailoring your experience - don’t be out off by parental controls or screen time instructions - that’s the best way to block things without breaking the OS.