Weird partition OS upgrade and how can I get rid of it?

[The Clark]

I have a 2017 MBP and it's great. I've had Windows and MacOS installed for a month with no issues when suddenly during a restart a new partition (some kind of installer) came out of no where and wouldn't let me boot directly into MacOS. How can I remove the highlighted partition in the image, and make MacOS boot default?

Note: This was my first restart after some OS upgrades so I'm assuming that's the cause.

EDIT:

I tried searching disk utility to see if there was anything I could delete but the installer doesn't show up there so I'm lost. I don't even need to get rid of it per-say, I would just like to be able to change the boot order.

 

[DeltaMac]

Boot to your macOS system (that would be the Macintosh HD, from your graphic)
Open System Preferences, then Startup Disk.
Make sure that Macintosh HD is selected as your default boot drive.
That will do the trick.

If you boot to your recovery partition, then open Disk Utility from the menu screen, you may be able to remove that odd macOS Installer partition from there.

 

[The Clark]

Boot to your macOS system (that would be the Macintosh HD, from your graphic)
Open System Preferences, then Startup Disk.
Make sure that Macintosh HD is selected as your default boot drive.
That will do the trick.

That did it. Thank you for your help.