I had also the same Issue with 4.9.xx LTS Kernel, which was forced by VirtualBox installation. Did done the steps which DataDrake mentioned, but that didn't work (the system always bootet into the LTS Kernel, even after LTS Kernel and VirtualBox uninstalling). So mounted the boot Partition and removed all LTS entries I've found, did a clr-boot-manager update
and rebooted. That worked for me.
So the questien is, why is the system forcing the LTS Kernel (and why VBox requires this Kernel, it should support Kernel 5.7?).