First, find information about canceling your account by logging onto AOL and going to Keyword: Cancel.
Then, before uninstalling the AOL software, save your e-mail addresses, not to mention your Internet favorites. Ask AOL tech support how to do so in the version you are using. There are too many versions to cover here.
That done, go to the Add/Remove utility in the Control Panel. AOL will be listed in the Programs window. Highlight the reference and click on the Add/Remove button.
In Control Panel/Network, remove AOL Adapter, AOL Dial-up Adapter, and TCP/IP AOL Adapter, if they are listed.
You may also have to remove references to AOL in the Registry. Go to the Start menu and click on Run. In the Open box, enter "regedit" without the quotes and click on OK.
When the Registry window opens, click on the Edit menu and then on Find.
Use "AOL" as a search term, without the quote marks. When a reference is found, right-click on it, then choose Delete.
Go back to Edit. Click on Find Next. Keep doing so until you get a message that the search utility can't find any more references.
Repeat the process using "America Online" as a search term, again without the quotes.
Don't be surprised if, after purging AOL, you have problems with your modem.
You may have to lean on tech support at your new ISP to help you clean the mess AOL made in your system.