By default, Skype keeps a log of your conversations with your contacts on its cloud servers, so your history can be synced across devices. While Skype features the ability to delete all history with all contacts, it doesn't support deleting history with individual contacts, as of publication.
Skype's history settings, as well as the deletion option, are located in the Privacy settings menu of Skype's general options.
Sign into your Skype account and click Skype, followed by Privacy to open the Skype options menu on the Privacy tab.
Click the Show Advanced Options button to expand the options on the Privacy tab. This expands the Advanced Options menu, which offers a lot of different options for how you receive IMs, calls and other messages and how long Skype stores chat history.
Click the Clear History button near the Keep History drop-down.
Click the Delete button in the Delete History dialog to confirm deleting your history. Depending on how much history is deleted, it may take several seconds to completely clear.
Click Save or Cancel to close the Options menu. Choose Save if you've changed any other settings.
Tips & Warnings
- Cleaning out your chat history frequently can be useful if you use Skype on several devices and/or computers and switch between them frequently. Each time you sign into Skype on a different device, it has to load all previous messages from your other devices, which can be time-consuming.
- If you think you might need to restore your history in the future, then do the following before deleting your history: Press "Windows-R" or select "Run" from the start menu, and then enter "%appdata%\Skype" without quotes to open the Skype AppData folder. Select the folder with your Skype name, copy the "main.db" file inside and paste it into another folder elsewhere on your computer. When you need to restore, just paste this file back into its original folder.