I just installed cc and lightroom on my computer. I already had LIghtroom 5. I asked if it would just update or if I would have to import all my photos and presets to the new one. They told me I would have to import. Well, to my suprised it just updated. Now...question is, I have the old LIghtroom 4 and 5 on my computer. Can I trash them with out causing any problems or loss??
No need to keep them around. You won't lose anything by deinstalling them.
Whoever advised you to re-import was way off-base.