Kind of curious what you consider a high ammonia level is? And pH for that matter.
If I remember correctly you added something to remove the chlorine? And you did a water change and added more dechlorinator (I don't know which one). That doesn't actually remove chlorine as much as it converts into other things, one of which is ammonia. These products also contain a ammonia binder that makes the generated ammonia safe. This binder in the dechlorinator is same stuff in Ammonia Lock.
Ammonia binders (dechlorinator, Ammonia Lock, etc.) make ammonia non-toxic to fish, but the ammonia remains in the water. Testing for ammonia will show ammonia, maybe high (whatever a person feels is "high"). So tomorrow, next week, you may again test for ammonia, see it's high, do more water changes, add more Ammonia Lock. Eventually the bacteria in the will probably be able to overcome all this and actually start to lower the ammonia and hopefully you will feel better and stop doing water changes and stop adding stuff.
Dechlorinator, Ammonia Lock, and other things have uses. But there are also drawbacks. These generally use acid as part of what they do, they mess with the water chemistry, and in general make it difficult for nitrifying bacteria to get started, that's the stuff you added from API on top of the nitrifying bacteria that were already in the pond and probably struggling because of the ammonia binders. So down the road you could actually have an ammonia and/or nitrite problem. But now it's really tricky because when you test for ammonia you'll have no idea if it's a safe level or a dangerous level. There are special test kits for telling whether you have safe or toxic because you won't be able to tell how much is bound and how much isn't. Something like MultiTest Ammonia from Seachem can tell the difference.
The last issue is the acid in these products. Your pH is high but that doesn't really tell you much, only what the pH in the water sample was. If the water has low KH it means the water isn't buffered against pH swings. For example, measuring the pH of distilled water is almost impossible at home. One minute the pH is 12 and a minute later it's 4. That's because pH is measuring the difference of something in the water (ions) not the amount of something. The less there is the more likely the test is off. KH measures the amount of the thing pH is trying to measure. So if you just measure KH you get more info, better info imo.
I say all that because you've been adding maybe a lot of acid and you've now added a lot of ammonia binder. That lowers KH. If KH gets low pH can swing. You test high today and low tomorrow. That stresses fish and also the nitrifying bacteria. KH is also one of the things nitrifying bacteria require in order to convert ammonia, so if KH is low the nitrifying bacteria will be slow and you could have an ammonia/nitirte problem down the road. And you're back to needing a better ammonia test kit to tell.
I know that all sounds complex, bah, bah, bah, nerd talk. I'm just trying to give you a sense of what you're doing to your pond and fish. I don't actually know because I don't know the actual numbers from tests, exact products, amounts, etc. Most people don't want to know any of this stuff. Luckily ponds don't actually need any of this stuff so for most people pond keeping is pretty simple. The problem is you're getting little bits of advice here and there. If you tell someone "I have high ammonia, what do I do?" the answer is water changes and ammonia binder. Standard answer. But if you also add "I add dechlorinator" if the person knows anything about ponds they can change the advice to "oh, then the ammonia is already bound, you don't have to do anything".
Luckily fish are very tough and can usually survive tons of cures being thrown at them.
One pretty safe thing you might consider is netting the pond so the remaining fish decide to jump. They can do that when water quality is bad in the hope of finding better water. I know you don't want to consider stopping the adding of stuff to the pond so a net is a little insurance.
