Mark the region where your print statements are and perform this:
^ *print.* enter
Which will delete all the lines in your region that match a line that has zero or more spaces followed by the word print, followed by anything.
You can wrap this up in a function if you'd like:
(defun delete-print-lines (beg end)
"Delete all lines in the selected region that start with the word print."
(flush-lines "^ *print.*" beg end))
I usually do this using multiple-cursors by selecting the give languages print function and using
mc/mark-next-like-this to select a bunch of them and deleting each line.
Similar to what Kaushalmodi was describing, if you are using git, and magit, you can leave them in and individually revert each printing line from your changes from the status buffer, or even by using
There are really countless ways to do this, you just need to find the one that fits you.