Using filters in CM will/should perform that task.
"Incompatible" simply means that the asset is too advanced for your particular version of Trainz.
For example: if you have TRS19 SP5 installed. This is compatible with assets with a Trainz Build up to and including 5.0 so build numbers of 5.1 and above would be incompatible. So a CM filter set to:- AND NOT
Minimum Build Number 5.1
... would filter out the incompatible assets.