No--at least not that way.
Alternative:
- Home city only has 1 shield.
- Spawn another unit with that city as home (the unit doesn't have to be in the city).
The first unit will disband (i.e. be killed) because the city will not be able to maintain both units--old units (unit that have that home city first) get disbanded before new units. OR if there is no maintenance (i.e. govt. is Fundamentalism and unit has 'Free for fundamentalism' flag checked) you could just delete the city via ChangeTerrain event or capture it (i.e. spawn powerful barbarian units next to the city so they will kill defenders and capture city). (Note that Fundamentalism flag just means the city doesn't use a shield to maintain unit but the unit still has that city as a home city thus will be disabanded as usual.)
If the unit is the only one in the game, you can have that unit type get upgraded (i.e. give owner civ obsolete tech--owner civ needs Leonardo's Workshop) to a nameless, invisible, immobile air unit (the unit won't die but it will no longer be active in the game.
If the unit has no city to stop in (as in a scen without cities or Airbases), you can do the same as above only upgrade the unit to an air unit with 1 fuel so that it will run out fo fuel (i.e. be killed) next turn.
Aside from that, I can't think of any other way to do it (assuming the unit is mobile, otherwise just kill it via CT event or Barbarian units as in the above examples).
