Really, don't bother removing code comments. Your source code doesn't make it to the user's phone - only the compiled code gets there, and that doesn't contain any reference to your comments whatsoever.
Android users tend to appreciate apps being as small as possible, so double-check you're only including resources (images, etc.) that are still being used in your app. Use OptiPNG/ PNGCrush on any .png images you have in your app - that can reduce the image file sizes by about 10%, which can be a significant part of your overall app size.
Also, use an audio editor such as Audacity to reduce the size of any audio as much as possible. Going for mono OGG Vorbis files is often best, and sounds plenty good enough on a phone.
