Assuming the net on the "noConn" net was called "net5", this will do it:
However, as soon as you do a "check", it will get reset. This is because the physical interconnect drives the connectivity, not the other way around - and any net not set by the schematic checker will get recreated. This is to help ensure that inconsistencies don't appear when connectivity is changed in the schematic - you could have ended up with two things which are still connected to the same net despite there being no physical connection any more (because the wire was deleted), and it would have to somehow know the intent of the user.
Of course, it's conceivable that we could have it that the connectivity in the database is more persistent, but right now it doesn't work that way.