#find . -mtime +50 -regex ".*\.csv" -exec ls -tl {} \;
find . -mtime +50 -name "*.csv" -exec ls -tl {} \;

 # find . -mtime +50 -regex ".*\.csv" -exec rm -f {} \;
# find . -mtime +50 -name "*.csv" -exec rm -f {} \;