There are many twitter based web services these days which may require you to enter your twitter username and password before you can use them, when ever you allow an application or web service to use your twitter account, it gets added under the list of applications which can access under your twitter account settings.
In order to remove applications to stop using your twitter account, may not post anything using your twitter account credentials, follow the procedure below.
1. Login to twitter.com – sign in with your twitter account credentials
2. Go to your twitter account Settings >> Connections – You will see the list of all applications
3. Click the link Revoke Access for the applications which you don’t want to grant access to your twitter account including read and write access.