What is the best way to kill someone with sentry turrets and bukers

A bunker player is indeed very hard to kill. They have little to no offensive units (just the ninja in reality) but they are notoriously hard to kill when attacking them due to the sentries and Bunkers.

In all honesty I would leave them be unless they either do something do deserve a beating or they have so much land you honestly feel it is a worthwhile course of action as trust me, attacking a bunker player wil hurt.

Now should you choose to go along with this I would suggest an RPG/F117 combination in an attempt to take them down. Both units have a high damage and both fire early which gives you the potential to kill the player before he is able to fire back at you. Terrorist Leaders and Sorcs have been suggested to do the trick however they will be firing after the bunkers and sentries and will take great damage

Hope this helps somewhat

Let me know if you need anything else :)