Can an Influence Disc be moved to an adjacent hex if there is no other influenced hex adjacent to that target hex?
When you move the influence disk, pick up the disk from the hex and place according to the rules i.e. 


to a hex that does not contain an Influence Disc or an enemy
Ship and is adjacent to a hex where you have a disc
or a Ship.
to a hex where only you have a Ship.


The disk cannot move across the explored space on it's own


  Q: Using the Influence action, I can move an Influence Disc from a hex to its neighbor through a Wormhole connection. May I move the Disc that created this connection in the first place?
  A: No. If you move the disc, there is no longer a connection.


Source: https://boardgamegeek.com/thread/711246/eclipse-official-faq