Both tourist and language course visa

To recap a number of points that have been made in the comments:

• Your type C visa is intended to cover several purposes, it's a "short-stay" rather than a "tourist" visa (although many people are confused about that and you will frequently come across sources describing it as a "tourism visa"). A short single or two-entry visa is implicitly tied to the specific trip described in the application and using it for something else could therefore be problematic but that's not the case for your visa. Incidental trips to other places than Spain are definitely allowed, no matter their purpose.

• Short-stay visas (otherwise called "type C", "Schengen" or "uniform" visas) can't be used to stay in the Schengen area for a long time and in particular not longer than 90 days in any 180-day period. Applying for another short-stay visa does not open any right to go over that limit and, in fact, submitting a plan that would involve breaking this rule is a reason to refuse the visa. So if you have already stayed in Spain in the 90 days prior to your French course, you will not be able to do it under short-stay rules, no matter what. Even having your Spanish visa revoked and applying for a French visa instead would not help you.

• If you have already used up your 90 days or want to stay longer than that in France, you need something else entirely, namely a French long-stay visa (type D visa). The good news is that it is possible to get these to study in France, even for relatively short courses (i.e. not necessarily for a full year) and it would not conflict with your Spanish visa (you don't need to have it revoked and time spent in France under such a long-stay student visa would not could towards the 90 day limit for the rest of the Schengen area).

  The bad news is that I don't think France would issue one for a language course or a three-month course (as opposed to a full-time academic semester at an higher education institution) and there might also be a concern that you are trying to skirt the rules. So if you want to do that, you need to check exactly what the consulate requires and apply for the right type of visa (do not use the form for short-stay visas). The rules and fees are also going to be different than what you are used to for your Schengen visa.

Note that if you already applied for another short-stay (type C) visa from France, I think that the correct course of action for the consulate would be to decline to process the application (return the documents and fee and stop there). I don't see how they could revoke a visa they haven't issued themselves in this situation. They would not issue a type D visa either since you would not have submitted the right form and supporting documentation.