If all my topics that I've started are deleted. Do I still retain my rank ? Junior , Member , Senior etc... ? ?
Your topic being deleted does not make you lose your position as JR or SR, except: all your posts are deleted, it can affect your ranking position.Example:
Currently you have 171 posts, while the topics you created are only 11 topics for now, if those 11 topics are removed the remaining 160 remain and subtract your activity from a total of 126 reduce the remaining 11 = 115 activity, thus you are still in JR's position.
This has been answered above.
If I decide to wipe my profile clean completely, will the rank stay ? 
You will return to the newcomer position, even though you have 1000 Merit.