A useful command frequently used in backup scripts is the find command.  The UNIX find command can locate files based upon the time the files were last changed, accessed, or modified using the -ctime, -atime, or -mtime respectively.  So, to find all files in a directory that are older than 7 days might look like this:

find /home/myuser -mtime +7 -print

If you are trying to remove files that are older than 7 days, you can use pipe the output of the find command to xargs. You will want to set the -r option for xargs in case there is no output. The -r flag in xargs tells the command to skip execution when there is no data.

find /home/myuser -type f -mtime +7 -print0 | xargs -o rm -rf

The command above will perform a deep or recursive search for any files in /home/myuser and remove them. The -print0 argument will enable this search to find files in that path that may contain spaces in the file names.