How can the United States repay our debt of around 19 TRILLION dollars?

No immediate need to.
About 70% of that is public debt, money we owe ourselves in the form of Treasury Bonds, etc.
A smaller portion of that is actual debt to foreign nations, which China is probably the largest at about 8%.

The U.S. debt isn't like regular debt like a mortgage or a car loan. The U.S. debt is reflective of investments that other people and institutions have made in the U.S. It doesn't need to be paid back all in one go.

You would never want 0 debt. Most of the debt is debt owed to ourselves, and if you have 0 debt that indicates the economy has ground to a halt. You want to decrease foreign stake in your debt, sure, but national debt does not work like personal debt, for many reasons.

stop going to wars, stop instigating other countries, stop sending our jobs to other countries, stop letting big oil and coal hold America back, change the way the military uses its funding, stop all military contracts that have stock holders in congress and in the military, and start taxing the rich by getting rid of all the loopholes that let them hide their money

By spending less than it takes in via taxes. The debt could be paid down/off if congress had the discipline to do it.

All you need is a president and congress with the political will to do it.

It will never be paid and Hillary will double it again just like Obama and Bush both did

By controlling spending and growing the economy. We have not done either in a very long time.

Trump had an idea to impose a special tax on incomes over $10 million to eradicate the debt within 8 years.