Uninstalling Linux

[sven1999]

My cosmo is triple boot (Android, Gemian, UBports). I am selling the device and interested buyers want only Android. How can I achieve an Android-only Cosmo?

[MonkeyControl]

I think if you follow the instructions on this page: 
https://support.planetcom.co.uk/index.php/Cosmo_Android_Firmware_Manual_Installation
you may be able to get back to single boot if you 'Reserve all space for Android' when you change the partition table, but I'm not sure, it may leave the multiboot in place and default to Android while retaining empty boot slots. 
One other option is this: 
https://support.planetcom.co.uk/index.php/TWRP_Manual_Recovery
I got this link from Planet when I was having network issues and wanted to rule out software issues.  Again I can't remember clearly if it left multboot options in place, but I think it removed them and took my Cosmo back to stock. 

[sven1999]

The first option worked perfectly. Thanks!

The only problem is that Android v25 cannot be installed in this way (not listed on the web page), so I had to use v23.

[gymbo]

The first option worked perfectly. Thanks!

The only problem is that Android v25 cannot be installed in this way (not listed on the web page), so I had to use v23.

But after that you should be able to install v25 OTA??

[sven1999]

But after that you should be able to install v25 OTA?

Yes.
But it would be better to have a v25 zip anyway.