I am using Skype API to make a video call.Till now video call is working fine.I used an Xml file to save Skype credentials(which are used to call any other Skype friend/user). B
Presumably, at some point you're using the credentials to connect to Skype.
Simply don't save the credentials until you successfully connect.
(I hope by "credentials" you don't mean "plaintext username and password".)