$ ag 'delete.*course_modules_completion'
course/lib.php
1086:    $DB->delete_records('course_modules_completion', array('coursemoduleid' => $cm->id));

completion/classes/privacy/provider.php
227:            $DB->delete_records('course_modules_completion', $params);
246:                $DB->delete_records_select('course_modules_completion', $deletesql, $deleteparams);
275:            $DB->delete_records_select('course_modules_completion', $sql, $params);
292:                $DB->delete_records_select('course_modules_completion', $deletesql, $deleteparams);

lib/completionlib.php
931:        $DB->delete_records_select('course_modules_completion',
950:        $DB->delete_records('course_modules_completion', array('coursemoduleid'=>$cm->id));

lib/moodlelib.php
5148:                        $DB->delete_records('course_modules_completion', ['coursemoduleid' => $cm->id]);
5170:    $DB->delete_records_subquery('course_modules_completion', 'coursemoduleid', 'id',

lib/db/upgrade.php
2161:        // Delete orphaned course_modules_completion rows; these were not deleted properly
2163:        $DB->delete_records_select('course_modules_completion', "