retract

abstract override fun retract(clause: <ERROR CLASS>): RetractResult<MutableTheory>
abstract override fun retract(clauses: Iterable<<ERROR CLASS>>): RetractResult<MutableTheory>
abstract override fun retract(clauses: Sequence<<ERROR CLASS>>): RetractResult<MutableTheory>
open override fun retract(head: <ERROR CLASS>): RetractResult<MutableTheory>

Tries to delete a matching clause from this theory