If you delete a splice with two wires attached, the wires heal and any control points on the wires remain. If there are three or more wires attached to the splice, the logical connection of the signal carried by the wires is maintained. Wires that are not required to maintain this connection are deleted. Only the properties from the wires that are kept are retained.
If you delete a splice from a segment, the two segments that the splice intersected heals, and all routed wires remain routed. If a segment or wire that has a splice on it is deleted, the splice remains. Any virtual parts assigned to the splice are also deleted.