Hello Aspirant! It's not good or possible for you to complete your B.Sc. degree in alternate years. If you've completed your first year in 2021 then you must complete your second year in 2022 itself. If you drop or fail a year that would be your loss though it would help you complete your second year in 2024 but you may lose time and reputation. Also not every university/institute allows a gap of 3 years or so. It's loss on loss. So I would suggest you, if not for any good reason, don't drop.
Hope this helps.

Most universities do not allow this much gap between years of your graduation. It depends on your university whether they allow this or not.

Every degree will have a time limitation as per the university academic regulations.

So, check your program (B.Sc.) regulations under your university.

All the best.