2017 Triumph Street Triple 765 Rs Coolant Change

Hi,

I just bought a 2017 Street Triple 765 RS and noticed the coolant was low. I had some OAT coolant in the garage which the maintenance manual says is fine to use but instead of mixing the two I decided to drain the coolant and fill up with the new stuff. However, I only managed to get about 1.5L out from the bottom hose and there doesn't seem to be a plug to remove the coolant from the cylinder block. Also, there is no bleed screws on the top hoses. Can anyone advice? I've attached some pictures. The manual just says "we recommend taking it to a triumph dealer" which isn't very helpful.