Do I have to teardown it to change the front glass?

So I broke my HTC U play glass some time ago and my friend told me that I might have to change the LCD as well as some phones have it attached to the glass. I don't really know much about this stuff so I wanted to ask if I have to go in from the back to change the glass or if I can just heat it and remove it and put the new one in. I have found some videos of people changing LCD but none of changing just the glass.