Strip HTML from textbox

I am allowing the user to leave comments.

Do I need to strip the user input from <g class="gr_ gr_9 gr-alert gr_spell ContextualSpelling ins-del multiReplace" data-gr-id="9" id="9">html</g> <g class="gr_ gr_10 gr-alert gr_gramm Punctuation multiReplace" data-gr-id="10" id="10">tags.</g>

And is there an easy way of doing that.

Thanks