Delete a very large object in C #

helicopter. I'm new to C #, and I got a big picture with GC removing objects that cannot be reached by my code. The problem is that I work with some large (7-40 MB) objects, it’s good that I don’t need all at once, is this any possible way to delete an object? I tried this:

- create big object X
- use big object X
  X = null; /*so I don't have any referance to it any more*/
  GC.Collect();
  GC.WaitForPendingFinalizers(); - create next big object ....`

Does this guarantee that the large object will be deleted after exiting GC.WaitForPendingFinalizers();?

I know that I have to implement my design in order to make objects smoother, but believe me, I tried, and this complicates the logic. If there is no other way, I will do it, the code will be 2 or 3 times larger.

thank!