Sample Code:
Set < Id > setContentVerIds = new Set < Id >();
List < ContentDocument > listFiles = new List < ContentDocument >();
for ( FeedComment objFC : [ SELECT Id, RelatedRecordId FROM FeedComment ] ) {
//Add your required where condition
if ( String.isNotBlank( objFC.RelatedRecordId ) ) {
//RelatedRecordId is the Content Version Id
setContentVerIds.add( objFC.RelatedRecordId );
}
}
for ( ContentVersion CV : [ SELECT Id, ContentDocumentId FROM ContentVersion WHERE Id IN: setContentVerIds ] ) {
listFiles.add(new ContentDocument( Id = CV.ContentDocumentId ) );
}
if ( listFiles.size() > 0 ) {
delete listFiles;
}