Since leafminerts seldom cause much more than cosmetic damage to any plant there is no real reason to do much about them. If you can prevent the adult flies from laying eggs on the affected plants or prevent those eggs from hatching, but once the larva is in the leaf there is little that will harm them.
You need tyo know which species of fly is laying the eggs and when it will do that so appropriat controls, Neem Oil or pyrethrin based sparys of dusts, can be applied properly.

You will not touch leafminers with those products unless you catch them in one specific stage of growth where they are external to the plant. They do not get through the protection of the leaf to do any good once the miner is inside.

Thumb and forefinger. Pinch to squish. I wouldn't worry about them personally.