Request Mapping: Remove Parts/Headers (8.0.1)

How can I remove multiple message Parts?

The manual says:

Remove parts/headers in the source XQMessage from the target XQMessage. This action is available
only when a source XQMessage is mapped to a target XQMessage and Reuse Source XQMessage is
Remove
parts/headers
selected in the Default Message field. This action uses a regular expression pattern to identify headers
and parts in the source XQMessage.

I figured out how to remove one Messge Part but I'm not very familiar with regular expressions or how to apply them in this context. Can someone show me an example for how to use a regular expression here and how to remove multiple message parts, say Matthew, Mark and Luke?

Thanks

Steve