I have a Dell 5437 Platform Notebook
  DOE40-HSW I need to exchange the PU4503 (tps51225), I would like a help or guidance on how to proceed with this component change (which technique should I use).

So, you have never replaced the smd component?
The simplest technique, you need to blow it with your Hot Air Gun / Hot Gun / Heat Gun, etc and then use a tweezers to shake it slowly and lift it.
If you replacing with the new one, first you need to solder the legs of the IC, to ease installing it.
To install it, you can put the IC, then blow it, OR blow the board for a while then put the IC slowly.