MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4
{DEALLOCATE | DROP} PREPARE stmt_name
      To deallocate a prepared statement produced with
      PREPARE, use a
      DEALLOCATE PREPARE statement that
      refers to the prepared statement name. Attempting to execute a
      prepared statement after deallocating it results in an error. If
      too many prepared statements are created and not deallocated by
      either the DEALLOCATE PREPARE statement or the
      end of the session, you might encounter the upper limit enforced
      by the max_prepared_stmt_count
      system variable.
    
For examples, see Section 15.5, “Prepared Statements”.