Hello NicholasArt, and welcome to the Unreal community.
Compiling shaders can be a bit annoying if it manages to disrupt your development processes. I understand your annoyance. Shaders are an integral part of development as you need them to properly display your materials. You may possibly reduce the amount compilation by creating material instances.
While I am not sure on how to outright delete shaders, I can provide you some relevant documentation on materials and material instances.
More information:
I browsed for a bit longer and found relevant information relating to foliage and if this is something that might interest you, you can find the solution here.
I hope this information assists you.