SWI-Prolog -- retractall/1

Documentation
- Reference manual
  - Built-in Predicates
    - Database
      - Managing (dynamic) predicates
        
        abolish/1
        
        abolish/2
        
        copy_predicate_clauses/2
        
        redefine_system_predicate/1
        
        retract/1
        
        retractall/1
        
        asserta/1
        
        assertz/1
        
        assert/1
        
        asserta/2
        
        assertz/2
        
        assert/2
- Packages

Availability:built-in

[ISO,det]retractall(+Head)

All facts or clauses in the database for which the head unifies with Head are removed. If Head refers to a predicate that is not defined, it is implicitly created as a dynamic predicate. See also dynamic/1.^{74The
ISO standard only allows using dynamic/1
as a directive.}