Official rule text
61.9 If an objective requires a player to destroy one or more units, those units can be destroyed by producing hits against them, playing action cards, using technology, or any number of other abilities that use the “destroy” terminology. a Forcing a player to remove a unit from the board by reducing the number of command tokens in their fleet pool is not treated as destroying a unit.
View official source
Source: Living Rules Reference and FAQ - Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 61.9