Hi @aryanbhesle
You will have to remove the motherboard from the laptop case to remove/replace the charge port, as it is soldered onto the motherboard.
Here's the [http://h10032.www1.hp.com/ctg/Manual/c02745864.pdf|maintenance and service guide] for the laptop.
Go to p.98/162 to view the procedure to remove/replace the systemboard. Once it is removed from the lower case, you can safely unsolder the power port from the board and solder in the replacement.
Search online for [https://www.google.com/search?client=firefox-b-d&q=hp+elitebook+8440p+dc+power+jack|HP EliteBook 8440p dc power jack] to find suppliers that suit you best.