The temporary files, history and cookies for Internet Explorer (IE) in Windows phone 8.1 can be deleted by a couple of ways.
The quick way
Open Internet Explorer and tap the dots icon.
Then choose “Settings”.
This will bring up IE settings screen.Tap “delete history” for deleting these web items.
Hit “delete” to empty all Internet Explorer contents.
The longer way
This is by accessing Storage Sense.  (Also, the amount of free space can be seen through the Storage Sense feature for phone and SD card.)
Go to Settings and choose Storage Sense. Next, select “phone”.
Scroll down to “temporary files”.
Tap on “Internet Explorer settings”.
This too will bring up the same “delete history” settings screen as before.
Regularly emptying these items can free up space as well.
Happy cleaning.