I've just discovered how to redirect the Linux SDKs for your RAD Studio installation, so if you intend to save space for your home drive, you can.

Open up the Tools, Options dialog, and navigate to the IDE's environment variables page.

Override the BDSPLATFORMSDKSDIR by clicking on Add System Override and setting it to a new location.

Once you've done this, you can either move your existing SDKs to the new location, or delete the current SDKs, and refresh them, so that the IDE will import them into the new location.