Windows – How to clear the Skype chat history

No they don't.

Skype archives your chats for you and stores them locally on your computer, if you have enabled this option. Chat histories are not stored anywhere on the Skype network. In other words, no one else will ever be able to see any of your chat histories except you and the person you are chatting with.

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Look for folder .skype rename it to something else like skype.bak (or just delete it). Then restart Skype.

You will need to re-enter your username and password. Your chat history should now be clear.