Alkaline hydrolysis. Since amino acids are water-soluble, you can even prepare an alkaline aqueous solution with NaOH/KOH (I would say 1 to 5 M may be sufficient) and put under heating/reflux for a couple of hours. Even if the methyl ester is not soluble, as soon as the product forms by alkaline hydrolysis it dissolves in water. In the end, you cool to room temperature and either evaporate the water (in this case you will have a glycine salt, since you are in basic environment) or recrystallize glycine hydrochloride after acidification of the water to acidic pH with HCl.

I would go for mild alkaline hydrolysis instead of strong. Use LiOH, Dioxane or THF, and Water. You may need 3 to 5 equivalent bases. Stir reaction at RT for 1h and Check TLC. In most cases, it will complete within 1h.

Use 3 equivalent LiOH in methanol at 5-10 degree, 2-3 hrs followed by usual work-up.