Hi Asuka_redo
I'm Jen, and I'd be happy to help you out with this issue.
I'm sorry to hear about this issue. It seems Bing has an issue revalidating Microsoft login to clear search history. I would suggest submitting a feedback to Bing. In the meantime, you may try these steps as a work-around. Go to
https://account.microsoft.com/privacy/ ,please make sure to sign in to your Microsoft account. Scroll down to Search History which shows the things you type when you search for information on the internet using Bing. Just simply click on 'Clear seach history'.
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.
Best Regards!
Jen :)