The most basic way is to move gw2.exe and gw2.dat from their program directory on C: to some new program directory on D: and adjust any shortcuts to gw2.exe you might have created. This way might require some basic Windows knowledge.
A way more suited to someone with less Windows knowledge is probably in fact uninstalling and re-installing to the new place. If you don’t want to redownload the huge gw2.dat file but re-use the existing one, do this:
- find the directory where gw2.exe and gw2.dat are currently located
- move gw2.dat from there to a temporary directory
- uninstall gw2. This should remove references and shortcuts to the old location.
- download the installer from the GW2 website (from “MY ACCOUNT”->download client) and install GW2 into your desired new directory on D:. This should create new references and shortcuts to the new location.
- as soon as the game is installed and is redownloading the game data, terminate it
- locate the new directory, where you will find a tiny new gw2.dat.
- move your saved big gw2.dat from your previous installation from the temporary directory to the new directory, overwriting the tiny gw2.dat
If you have plenty of download bandwith and even less Windows knowledge, then simply uninstall GW2, then download the installer from your account management, and reinstall to the new directory and let it download the whole client.
Your customizations and your GW2 account are kept with each way, because they are either saved in a user-specific directory on your machine that is untouched during uninstall/reinstall, or on your GW account on the Arenanet servers that is also untouched during reinstall.
