find
is the common tool for this kind of task :
find ./my_dir -mtime +10 -type f -delete
EXPLANATIONS
./my_dir
your directory (replace with your own)-mtime +10
older than 10 days-type f
only files-delete
no surprise. Remove it to test yourfind
filter before executing the whole command
And take care that ./my_dir
exists to avoid bad surprises !