Remove many many many files from a folder

As I can see you don't need to remove your dir , only files inside. So you can recreate it

rm -r /path/to/dir && mkdir /path/to/dir

or even delete only files inside

find /path/to/dir -type f -delete

afair first one works faster.

UPD. Note that way with find might be not optimal from space consumption point of view, as directory size will be reduced only after fsck. Details.

Workaround #1:

find /path/to/dir -delete

Workaround #2:

rm a*;

rm b*;

rm c*;

etc