Q.rockroses & roses
Should you cut of the flowers as they die off during the growing season?
Sure. For the roses dead head by cutting below the leaves just below the flower and above the next set of leaves down. Right above the second set of leaves down from the flower. You should see some new growth forming at the node at this point I haven't dead headed rock roses, Cistus, if we are talking about the same plant. You can prune them back during the season if the plants are overgrown, but deadheading will encourage the plant to rebloom without removing any stems responsible for the next set of blooms.
Most rosebushes need deadheading (the removal of old spent blooms) in order to repeat bloom well. The exceptions to this rule are the Knockout roses and the Home Run line of roses, for those you just pull the old dead petals off to tidy them up and leave the rest.
For rock roses I believe you are referring to Portulacca's or Moss Roses as they are sometimes called. You do not have to remove the flowers when they are done but the overall plants look better if you do. They will continue to bloom either way just fine.
