Delete dimensions (select dimensions) in sketch

Via a macro or via the user?

You can use a selection filter for that. Display the filter via View > Toolbars > Selection filters and enable the dimensions button. I've never used it before, but it works surprisingly well

You can also do it this way

Our use the Select All command (Ctrl+a).

If you don't pre-select anything, it will select everything in the sketch.
If you pre-select a dimension and then hit Ctrl+a, it will select all dimensions.

If you pre-select a sketch entity and then hit Ctrl+a, it will select all sketch entities.

I hope this helps,

Jim