The DelDimSSet is to delete the Dimensions from the ActiveSelectionSet (per the original question) I also ask if these are the ones you want to delete. Then DelDim allows you to select more dimensions if you need to, if no press enter. This way if there are dims in the active selection set they are deleted, and you are asked for more. or if there are no dims in the original ss you are asked if you want to select some to delete.

BTW you can modify this to include any entity or entities you want. You can filter by layer, entity type.

The change below will select all entities on the layers "STEEL", and "HOTROLLED", but if it is a hatch it will exclude it.

[VBA]
Sub DelDim()
Dim ssetA As AcadSelectionSet
Dim gpCode(6) As Integer
Dim dataValue(6) As Variant
Dim groupCode As Variant
Dim dataCode As Variant
' gpCode(0) = 0
' dataValue(0) = "Dimension"
gpCode(0) = -4
dataValue(0) = "<or"
gpCode(1) = 8
dataValue(1) = "STEEL"
gpCode(2) = 8
dataValue(2) = "HOTROLLED"
gpCode(3) = -4
dataValue(3) = "or>"
gpCode(4) = 67
dataValue(4) = 0 '
gpCode(5) = -4
dataValue(5) = "<not"
gpCode(6) = 0
dataValue(6) = "hatch"
gpCode(6) = -4
dataValue(6) = "not>"

groupCode = gpCode
dataCode = dataValue
Set ssetA = Aset("DimDelete")
ssetA.SelectOnScreen groupCode, dataCode
While ssetA.Count
ssetA.Highlight True
ssetA.Erase
ThisDrawing.Regen acActiveViewport
ssetA.SelectOnScreen groupCode, dataCode
Wend
ssetA.Delete
End Sub

[/VBA]

Sorry I am rambling again ROFLMA