First of all I agree with leaving them alone. However I will provide the solution because there are individuals out there that will protect their programs at all costs trying to make themselves important or trying to ensure job security.
Step 1. Take a back up. It may turn out you need those programs after all.
Step 2. The programs you can't delete are likely in the macro table. Find and note the macro number(s) of the program(s) you wish to remove.
Step 3. Put the robot into a controlled start.
Step 4. Go into the variables and look up macro table variable.
Step 5. For the corresponding macro table entry numbers that you wrote down. Change the system mask of those entries to a 0 (they are probably set at 3).
Step 6. Cold start.
Step 7. Go into the details of the affected programs and you should now be able to turn off write protect.
Step 8. Delete the desired programs.
Like I said. I agree with the sentiment to leave the programs alone if possible. But if you insist on doing this, I remind you once again to take a back-up first.