That may be all you need to do, anonymous. Give it a pool and let it do the rest, that is. A squirtle will know by instinct how to swim, as well as how to use its basic water-type moves, so you won’t need to teach it yourself. You can simply place it in the same vicinity as the pool, and it will know what to do.
What’s more important, though, is your fear of water-types. Your fear of water may resolve itself over time through exposure therapy (that is, the longer you care for your squirtle, the more you’ll be able to tolerate water), but the problem is that you won’t be able to receive that exposure therapy unless you’re certain you can handle your squirtle. It sounds like this squirtle is among the water-types you can handle, certainly, but nonetheless, think hard about whether or not this is something you can do. If the answer is no, then it’s far better for the both of you psychologically if you rehome it.
Rehoming may be a tricky process for a pokémon so young (one that’s imprinted on you, no less), so it must be done carefully. First, find a reputable foster pokémon organization that will help you find a foster trainer. The caretakers in this shelter must be as caring and attentive as possible, as surrounding your squirtle with caring people will make the transition easier. Next, once a foster trainer is found, work with them for the first week in order to establish a relationship between your squirtle and its new (temporary) trainer. (If one isn’t found and you must rehome your squirtle immediately, simply work with the staff of the shelter instead.) Lessen your presence little by little over time until the squirtle is comfortable without you in sight.
Alternatively, if you don’t want to place your squirtle in a shelter or a new home, train yourself to tolerate your squirtle’s presence, perhaps through exposure therapy as well. If you have a partner or someone who shares your home with you, ask them to help you care for your squirtle, but make it a point to spend a period of time each day with it. If you live alone, simply have it play in the pool or a bathtub as much as possible, then interact with it when you need to care for it. (As a note, yes, it’s young, so you will have to spend time with it. Furthermore, you need to remain calm during these moments, as any indication that you’re afraid of your squirtle will have adverse psychological effects on it. I highly recommend meditating before attempting to interact with your squirtle in order to calm yourself.) During these time periods, do something fun to engage with your squirtle: a game, a bit of (non-water-based) training, exercise, and so forth. Increase the amount of time you spend with your squirtle each day until you get used to its presence enough to feel comfortable around it.
As a note, this may not completely cure your fear of water-types in general, but at the very least, growing used or even close to a single water-type may help you handle brief interactions with others. If you wish to rid yourself completely of your fear of water-types, you’ll need to confront both your past traumas and the fear itself. Professional therapy may be a good idea.
Best of luck, anonymous!