it does not matter what material type the material has, material types do not control if a movement has to be posted in WM too. This is just controlled by the plant/storage location which is assigned to WM.
If you want send ERSA material from a different picking location, then you have to have a second picking location in IMG: determine picking location
And you can only add a second location if you differ by a storage condition. Hence create a storage condition "no WM" maintain it to all your ERSAs with MM17, add a record with this storage condition and a different storage location in determine picking location.
It is in general no foreseen to remove views from a material master. The only option would be marking the location for deletion in MM06, and run archiving for MM_MATNR. But you need a modification to be able to archive a certain organisation level only, as the standard archiving can only archive a material entirely. This modification can be found as OSS note in Service Marketplace.