To shutdown I think better proper way i.e long press power button on remote you'll see small pop up on screen where you can select shutdown/restart/screenshot.

Or you can set power button to shutdown on single click, there is a setting on that on settings menu (powerkey definition).

U dun have the remote?

Without remote, only way is to cut power.

Use mouse , pull up from bottom screen to reveal the Navigation bar.

You will see a power button icon at the far right of the bottom corner. Click and hold the click until a pop up appears allowing you to power down or restart.

Or if lazy, just unplug the DC adapter at the back of the box. I see others doing this, but I rarely do it.

Or you can set the Power Key Definition in the Side bar setting to Shutdown. Then everytime you click the power button , it will initiate shutdown sequence instead of sleep/standby.

boy, u still refuse to say if u have the remote.

u lost it or what?!!

Seems like you are using an official Tanix Tx3 or Tx6 box with Alice Ux. Did you upgrade your Tx3 firmware to get the Alice Ux?

Majority of us bought OEM Tx3 boxes from China sellers, in fact if you check majority of Tx3 sold are OEM Tx3 and not Tanix Tx3.
Hardware wise there are no major differences, some times only wifi bluetooth module diferences. Firmware wise, I believe this is one of many examples of  OEM factories updated the original firmware to make it better and lighter.

Let me check on the Alice UX to see if your Tanix Alice UX can set the Power button to shutdown instead of standby.
I have read other Tx6 users having this exact problem on how to shutdown even with an IR remote.

Do check with sellers like shopee.com/linglang.my if an IR remote can help you or not. I think it costs less than RM10.

hv remote but dun wanna use.

TX6 but this is TX3 thread.

sorry, i misunderstood.

Sorry can't help. Your lucky, yours have a navigation bar. I don't remember my old Tx6 has any navigation bar at the bottom.  Totally different firmware to yours.

Been asking around the Alice UX in the new Tx3 mini Android 8 has all these features brought over from Android 7.

I believe the Tx3 Android 9 would have it too. Again, all these are OEM boxes, not the originals Tanix.