No, you cannot choose the drive you get - Dell uses drives from many manufacturers. Nor can you order the system without the SSD (and you don't want to do that anyway, because it would void your system support).
If you want to order a gaming system down to the last detail - even to the brand of thermal paste you want, you can do that. There are plenty of boutique builders that cater to this market - all of which sell Clevo-built systems. Sager, AVA, Falcon Northwest, Eurocom, Xotic PC, etc. are all in this business. Dell is not - Alienware is a mass market brand. You'll likely pay more for a custom build - but that's the market Dell does not cover, even with Alienware.