Replacing formerly half-hot converted to always-hot receptacles with NEW receptacles
Disclaimer - Not an electrician

If I were to do this as a professional job, I would surely verify the switch leg, or red wire in your case, was not supplying/disrupting power to any outlets or lights. Upon verifying, and since you've capped the line off at each outlet's junction box, I would likely cut the wire just long enough to cap it with a wire nut and wrap it in electrical tape.

This should make it clear to you, or future owner, that wire no longer has any purpose. I would also be tempted to go back through each outlet's junction box and repeat the process. You might remember a couple years down the road what you did today, but becomes more of a gamble as the years pass by.

Short of getting into the walls and pulling out that run, that's probably the next safest thing to do.