How can I remove the bitartrate anion from an organic bitartrate salt?
I see on Wikipedia: "Dimethylethanolamine (DMAE or DMEA) is an organic compound with the formula (CH3)2NCH2CH2OH. It is bifunctional, containing both a tertiary amine and primary alcohol functional groups. It is a colorless viscous liquid. It is used in skin care products."

Now the fact that it is used in skin care products does not make it safe: the SDS  (https://www.fishersci.com/store/msds?partNumber=AC116180010&amp;productDescription=N%2CN-DIMETHYLETHANOLAMINE+1LT&amp;vendorId=VN00032119&amp;countryCode=US&amp;language=en) shows these pictograms: 



Uh oh! Oh, well. 

Well, let's forget that for a minute. DMAE is a liquid, boiling at 134C. Bitartrate anion is very insoluble if attached to potassium (potassium bitartrate is cream of tartar). If you added a stoichiometric amount of potassium bicarbonate (KHCO3, quite safe) to an aqueous solution of DMAE, you would precipitate almost all of the bitartrate, leaving the DMAE in water. Filter off the ppt and distill off the water and then distill and collect the DMAE. It will probably be a little wet and you will hate the overwhelming fishy smell.

Oh, and use a respirator (from the SDS: "Follow the OSHA respirator regulations found in 29 CFR 1910.134 or European Standard EN 149. Use a NIOSH/MSHA or European Standard EN 149 approved respirator if exposure limits are exceeded or if irritation or other symptoms are experienced.")

Good luck. Actually, I think you will have better luck if you do something else.