Is it possible to convert myBB to another software like vBulletin or IPB or phpBB or any other one?
huh?
maybe ask on their forums,
unless you want to convert another software TO myBB then yeah use the merge system
vB has an merge system, contact them.
Why would you even want to do that?
MyBB is the best forum software ever?
This is MyBB General Support not vBulletin you should go onto their support forums to find how to go back to their software.