If you don't want to delete the entire folder, then you can delete just the following items:
CoFHCore-1.5.1.5.jar
Galacticraft-1.5.1-a0.1.34.186.jar
immibis-microblocks-54.0.9.jar
[1.5.1]TreeCapitator.Forge.1.5.1.r01.uni.coremod.jar
If you delete those files, your tekkit should start up just fine.