Yes. If you are Level 6 or above, you can go to "Inserts and Related Sets", find the parallel set in question, and click the little "edit" buttom off to the right (it looks like the "edit" icon for a forum post). Underneath the fillable fields, you will see three options:
Edit Checklist
Update all card numbers for this set
Update all notes for this set
Clicking the third one (update all notes for this set) will allow you to do a multitude of things. In this case, you'll want to select "Find and Replace". Then put "RC, " in the "find what" box (without quotes) and leave the "Replace with" box blank. Hitting "Update" should pull all of the instances of "RC, " in the Note field out of the checklist, and leave you with just "SP". This same method can be used if it is determined that the "SP" Note needs to be removed too. You could also specify the number range you want this to be applied to if necessary, though it won't matter on this checklist.
It's important to notice one detail here, however. In the "find what" box, you need to enter a space after the comma. It should be "RC, ". Otherwise, the space stays and the new Note is " SP". I hope this helps - it definitely makes this a lot easier to update than going one at a time. Unfortunately, this only works for inserts and parallels, not base sets of Major Releases.
Nec Aspera Terrent
I'll never quit collecting entirely, but I am downsizing. Check out my COMC store and help me thin out what I don't want so I can buy cards that I do want. See something you like? Send me a message on here, and we can knock the price down quite a bit. I'll even take a bit of a loss if it means getting you a card you really want.