If you delete a splice with two wires attached, the wires heal. If there are three or more wires, redundant wires are deleted along with their associated properties. The logical connection of the signal carried by the wires is maintained.
If you delete a splice from a segment, the segment heals and all routed wires remain routed. If a segment or wire that has a splice on it is deleted, the splice remains. Any custom virtual parts assigned to the splice are also deleted.