In Gmail, at the bottom of the page it says Last account activity. Is there a way to clear the history? When I click on “details” it shows the history and I'd like to delete it.
The point of this feature is to detect intrusion into your account; if an intruder was able to disable the feature that would largely defeat its purpose. Given this, and no evidence to the contrary, I conclude this activity report can't be disabled.
It's not possible to clear the history in Gmail Last account activity as this is a feature to help the account owner to learn few details of the last access to his account.
From the reference
What is 'Last account activity'?
Last account activity shows you information about recent activity in your mail. Recent activity includes any time that your mail was accessed using a regular web browser, a POP client, a mobile device, a third-party application etc. We'll list the IP address that accessed your mail, the associated location, as well as the time and date.
If you're concerned about unauthorized access to your mail, you'll be able to use the data in the 'Access type' column to find out if and when someone accessed your mail. For instance, if the column shows any POP access, but you don't use POP to collect your mail, it may be a sign that your account has been compromised.