how to block people from deleting browsing history in chrome

There is not a solution about that. u need give others a warning.

Unfortunately, there's no such an option in chrome. But you can go another way to achieve your goal.
Create a separate user account that your family and friends can use when they use your computer, then change the password on your user account and don't tell them what it is so they are forced to log onto the account you give them access to.

HI,

for XP user,

restrict someone from deleting the firefox browsing history,

There is a "Turn off "Delete Browsing History" functionality" setting in the group policy for XP (

run gpedit.msc

under User Configuration -> Administrative Templates -> Windows Components -> Internet Explorer) that can be set to disable this functionality.