Hi,
a warpgate link is still visible on the map, even when one or both warpgates were destroyed or deleted.
Reproduction
1) Spawn two warpgates.
2) Link them (both directions).
3) Wait until the links appear on the galaxy map
4) Shot at the first station and wait until it overheats and explodes.
5) Shot at the second station and wait until it overheats and explodes.
6) Look for the next 5 minutes at the galaxy map. One or both links will not disapears.
Variant:
Destroy the stations with /destroy_entity.