empty the trash. If the application is in a folder along with companion documents like readme PDFs or text files, and there is nothing else in that folder you want, then drag the folder (hence, its contents) to the trash and empty the trash. Any tiny preference files are not worth hunting for to free hard drive space. Mac OSX is not like Windows (so you don't need to worry about unneeded registry entries or DLLs or any other files buried throughout the filing system hierarchy...
What "clog" are you talking about? I've been using/supporting/working with and on Macs and Windows machines for many years and have never heard that term used to describe a computer's behavior.
If the machine seems to be getting slower, there may be an issue with available hard drive space... How much available space do you have?
Or, if you run lots of widgets in Dashboard, there may be unnecessary CPU cycles being wasted on widgets you don't use. How many widgets are you running and how many of them require real-time updates (hence CPU cycles)?
My first recommendation is for you to increase your electronic RAM to as much as the machine can do. If this is already done, then find out what other processes are running (use "Application Manager" in your Utilities folder) - don't quit the processes, just find out what's running and let us know - and we'll take the next steps...
Hey, I just got my mac last summer and the problem with un-install just keep bugging me.
How do I unistall applications and make sure that it did leave anything behind cause I think my mac is clogging up because of that ^_^
please tell me cause I want to use mac more but the clog up really slowed down my macbook
)

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