@alikohail time to take it apart and to lean it. Remove all dust and debris from the air inlet vents as well as teh rest of the interior. Use a small brush for that. Clean your fan. After that, you may even consider replacing your fan if you are unsure of it works right.
Last but definitely not least, you want to reapply some new thermal paste. Anytime a device overheats, it is best to replace the old paste with some fresh one. Since iFixit does not yet have a specific guide for your computer for that, use the guide from something like this [guide|157050] to get an idea how to do it.
To work on your computer use the [document|40382|HP ProBook 450 G7 Maintenance And Service Guide] Page 56 deals with the heatsink.