Hi I have had a look into this for you and have found a couple of articles in the Knowledge Base that should help you. This [https://support.mozilla.org/en-US/kb/using-tabs-firefox-android article] will help you remove tabs when you have finished using them. This [https://support.mozilla.org/en-US/kb/clear-your-browsing-history-and-other-personal-dat article] will help explain how to clear your browsing history. I hope this helps, but if not, please come back here and we can look into a different solution for you.