I Can't Get the Slime into the Tube

I was very excited to use the bottle of Slime Tube Sealant that I purchased, as Slime Tube Sealant prevents and repairs flat tires, seals instantly and uses non-toxic fibro-seal technology, which is exactly what I needed to fix the slow leak in the back tire of my mountain bike, but, despite repeated efforts with various tools (including a pair of needle-nosed pliers and the top of the Slime Tube Sealant bottle, which claims to be a device for exactly this purpose) I couldn't get past instruction #2, even with help from a Youtube video-- and if you can't remove the valve core from the Schrader air valve, then you can't get the Slime Tube Sealant into the tire tube . . . so it's back to the bike shop for me-- I'm sure they've got a tool for this sort of thing, and I'm sure I'll feel like an idiot when I explain that I couldn't remove the Schrader valve core from my bike's back tire (even with the included tool) and that I couldn't motivate myself to remove the back tire of my bike and prize the tire off the rim and switch the tube myself, because I'm lazy and get no satisfaction from working with my hands because I'm an effete useless bastard who just wants to ride his bike but doesn't wanted to do any of the maintenance associated with riding said bike.