Cedar? As in Western Red Cedar?
Yes, you can plane the glue off as long as it is dry.
If it is cedar, it is not you or the clamp time that caused the glue failure. It is the glue and the wood.
I had some spectacular failures with TBIII and WRC a year ago, and talked to the glue techs. It turns out that in about 10-20% of WRC has a high enough resin content to repel the glue absorption.
Look at your failed bond - the glue has not gone into the wood, and is gummy since the wood did not absorb the moisture - it repelled it.
I was told to clean the surfaces to be bonded with a clean rag and acetone, and wipe until no brown came off the wood anymore. Then it can be bonded, right away. Try doing that to mortise and tenon joints!
We tried it on some boards, and it will work, but I did not feel confident. We would have to spend a lot of time wiping it all down since you can not tell which boards have the high resin content by looking.
The glue tech explained that any water based glue (aliphatics, urea resin) will have the same problem, but solvent base glues will not (epoxy, urethane, resorcinol).
This bit o' info is little known amongst woodworkers, and I see cedar glued this way all the time. But not by us anymore.