If you do what Mark Clarkstone said but in the Tvheadend web interface assign your own channel numbers to channels, you can put them in any order you want. So if you want them in alphabetical order, number them so they are (give the first "A" entry channel number 1 and so on), though I realize that's kind of a pain. You can click on the channel numbers to change them but after changing one or more click on some other unrelated part of the page and only then click the Save button or you will lose the last change you made. Also click Save after every few changes or you may wind up having to redo a bunch of them! Be aware that you can use the "number operations" button to move all highlighted channels up or down a number, in case you need to insert one or you need to close a gap.
Kodi may still show its own channel numbers but to remove those you'd probably need to talk to the author of whatever skin you are using in Kodi. Unfortunately some Kodi developers seem to not care that much what users want so if the skin doesn't already support hiding the channel numbers it may be an uphill battle to get that added. I have put channels in groups and within those groups they are in alphabetical order, but I still see channel numbers in Kodi and I just ignore them.
(I don't understand your comment about "channel numbers are being assigned in the sequences of 10000" unless that's how the channels are numbered in Tvheadend, otherwise I have no idea why Kodi would do that in your case).