How to clean up R memory (without the need to restart my PC)?

Question

I am running my code in R (under Windows) which involves a lot of in-memory data. I tried to use rm(list=ls()) to clean up memory, but seems the memory is still

Answer 1

I've found it helpful to go into my "tmp" folder and delete all hanging rsession files. This usually frees any memory that seems to be "stuck".