Cleaning up my wordpress installation from old plugins…

Hello everyone.

I accessed the central network administration of my website, and I have found something a bit puzzling.

First of all, I don’t even know why I have a central network administration. Initially (more than a year ago), I had installed wordpress 3.0 so that I could run simonmas.com as the central hub of various sub-websites, one for the music theory articles, one for my albums, etc.

After some months I realized I was being a fool. After a crash of the website in december 2009, I decided to start afresh, reinstalling everything, and rewriting the articles I had scattered in 3 or 4 sub-websites into the main one. I can’t remember if I asked the good people at bluehost to erase everything, but I do remember reinstalling wordpress from scratch.

My first question is: how is it possible that I still have a central administrator panel on top of my dashboard? I am not running a website hub anymore. Shouldn’t the format have erased all the changes I made?

Also, I’m seeing all kinds of data stored in the network administration page… including settings for plug ins that I have long disinstalled. They are not on the server anymore, nor in the plug in list anywhere.

You might have guessed by now that I don’t have an extensive experience… could anyone tell me what to do? Should I leave things as they are? Are all of these data going to slow down the website?

Thank you