How to remove glitters from glue
Depending on the glue, there might be solvent available. Dilute the glue a lot (the one containing the glitter), use a sieve to separate the glitter from the diluted glue.
Repeat until the glitter is clean enough. If you are lucky, the solvent of the glue will evaporate and you will be able to salvage the glue also.

Easier method: throw the mess to the garbage and buy new glue and new glitter.

@rebusB posted a very useful comment (thank you):


Unless it is water soluble glue like Elmer's or actual gold in the glitter, the labor, toxicity of solvents, and likelihood of it being a huge messy waste of time makes letting the gluey glitter go a better call.

OR just use the glue glitter as is.