To get rid of OpModes created by Block Programs, you must follow the directions to bring up the Blocks Programming Interface, then select the op-modes you wish to delete and select the "Delete Selected OpModes" buttonF
For the OpModes created in Android Studio. Type ctrl-shift-F in Android Studio in order to search, then type in the name of the OpMode you wish to get rid of on your phone. Then you must make sure there a "Disabled" associated with the OpMode, so it doesn't show up on your phone. Note there may be a missing import (import com.qualcomm.robotcore.eventloop.opmode.Disabled) that you can add by "alt-enter" in your Android Studio, assuming you have the auto-import option turned on (see the Setup and Install JDK and Android Studio tab) on this RNRR Software web-site for instructions on how to turn on the Auto Import feature of Android Studio