Delete all files older than X days

First, be sure you are in right folder:

if [ -z $PT_MYSQLBACKUPPATH ]; then
 echo "No PT_MYSQLBACKUPPATH set. Exit"
 exit 1
fi
cd $PT_MYSQLBACKUPPATH
if [ $? != 0 ]; then
 echo "cd to PT_MYSQLBACKUPPATH failed. Exit"
 exit 1
fi

You can remove files older than n, in your case:

find -mtime +14 -delete

Deletes files older than 14 days.

More complicated (definitely not optimal, though) solution for your question:

# Get list of newest files. If newest files are first, use head -n 14 instead of 
# head.
files=(`ls | sort | tail -n 14`)
# Loop over all files in this folder
for i in *; do 
 preserve=0; 
 #Check whether this file is in files array:
 for a in ${files[@]}; do 
  if [ $i == $a ]; then 
   preserve=1; 
  fi; 
 done; 
 # If it wasn't, delete it (or in this case, print filename)
 if [ $preserve == 0 ]; then 
  echo $i; # test first, then change this to "rm $i"
 fi;
done

You shouldn't use find ./* because this causes the shell to expand the wildcard before invoking find which will fail if there are too many files.

Instead, you need to pass "./*" to the find command like this:

find . -type d -path "./*" -mmin +60 -exec rm -rf {} \;