This function removes all occurrences of a specified HTML tag from a supplied string. Typical usage could for example be to remove unwanted or dangerous tags from the HTML body of an email message before displaying said message on an HTML page.
Use the additional bit-arguments to specify whether the tag should be treated as self closing, or when not self closing, whether the tags inner-HTML should be removed together with the tag.
The special case of a null-string will give a return value of null.
The processed string.