Learn About the macOS Mojave Downgrade Options
If you decide macOS Mojave isn't for you, you can downgrade to macOS Mojave, but it will take some time. It's a good idea to look at this process now, so that you are prepared in case you need to do this.
The downgrade process is smoothest with a current backup of your Mac on Time Machine. To downgrade, you basically erase your Mac and then install the Time Machine Backup from macOS High Sierra.
Spend a minute making sure you have a good backup and looking over the downgrade process so that you know what you may be getting into. This guide is for High Sierra, but it is practically identical.