I don't think Easton makes a "stock" collar for Axis arrows. The only collars (sometimes referred to as sleeves or footers) I'm aware of are made by Iron Will and Ethics Archery. It's possible to make your own from an aluminum arrow shaft of the appropriate ID, but the DIY route is probably more trouble than it's worth. You don't have to use a collar at all. Some guys choose to use them to reinforce the front end of the arrow shaft; others just use a HIT only and leave the front end of the shaft bare.
If your half-outs were installed with epoxy, I wouldn't count on being able to get them out. You could try the "drill bit trick" (remove nock, insert drill bit slightly smaller than arrow ID, hold arrow upward, swing arrow downward so drill bit slides forward and hits the half-out), but there's a risk (especially with aluminum) of deforming the backside of the half-out and causing a bulge in the arrow shaft if the adhesive bond doesn't break. If they were installed with hot melt (unlikely unless you did it yourself), the half-outs can be easily removed. If you have length to spare, you could consider just cutting the shaft behind the half-out.