Hey there, Salvatore.
Taking a drive out of its enclosure is not recommended. This will void the warranty of the drive, plus you might damage the HDD in the process of removing its enclosure.
The WDPiDrive Enclosure Blue Square is meant for that setup specifically, so it’s quite possible for you not to be able to fit a SATA to USB adapter in there. However, if you decide to try that with a different 2.5" SATA drive, you should do it at your own discretion. The mounting holes should fit as the PiDrive has standard dimensions for them: PiDrive dimensions.
Hope that helps.
CK_WD
