There appears to be no setting to omit pictures in replies. This is a feature of almost all email apps.
Most peeps normally just (manually delete) any inline or attached pictures when replying or forwarding.
It depends on how the images were originally added to the message…
If they are embedded in the message, and you reply to the message, the complete message is quoted below your reply. So embedded content is included because it is part of the message code. If you don’t want to quote the whole original message, just delete the parts you don’t want to appear in your reply.
If they are attachments, they are not included in your reply.