Simple Question
 

I used the try method of Zorin now I want to install Zorin, When I choose install it says it will erase Ubuntu 18.04.4 LTS. I put the Zorin on a USB stick will the erase only apply to the USB stick or is it going to reformat my hard drive?

I'd remove power and or data to internal drive if I wanted to preserve it.

Welcome to Linux forums.

From where I sit the answer is it depends upon what you tell the installer to do.

If you tell the installer to place Zorin on a usb, that is where the install should go.

However if you tell the installer to wipe the HDD that is exactly what will happen.

If you want a guarentee that it will not wipe your existing OS, you need to speak to the person controlling the install. ie you.

Just in case you do something wrong make an external drive back up of EVERYTHING you even remotely want to save BEFORE starting the (or any) install.

You should, promptly, get into the habit of having and keeping a current copy of your data on an external drive.

I haven't messed with Zorin in a long time, but, if dual boot is your goal, you likely need to resize your existing partition(s) to make space adequate free space for Zorin, then point the installer at the freed up space. This likely means you need to select "Advanced" or "Custom" or some such wording when you get to the partitioning step in the install.

A web search for "zorin" dual boot will turn up many tutorials that you would find helpful.

Also, as quickbreakfast pointed out, it's important to back up any files you wish to keep safe, you should back them up to external media.

I may have read that wrong.

If you have a single usb created of any Linux and you start the installer you can not use that current single usb. (well, really smart ones could)

You would be safe to get a second usb to install to after you remove the internal drive.

If you only have one usb then you need to burn a dvd.

I have on some distro's made a virtualbox boot of some linux and then installed it to the attached usb. Some distro's that need reboot to finish fail.

Also we may need to know uefi secure boot answers.

This would only be a simple question if you showed a photo. Nobody can guess what you have it set to do without seeing what you have it set to do. Usually the default option if you just hit enter is to wipe the first hard drive and install Linux there as the only OS.

You might also get a better answer if you explained a bit about what your goal is too. For example, how many hard drives you have, which (if any) OS(s) are already on them, if you want to keep any of them, etc.