The kickstart lever is not on a spline, it is located by means of a wedge pin. If you can turn it 360 deg, then that pin has been removed and you should be able to pull the lever off the shaft, it might need a bit of rocking.
You mention splines so are you maybe meaning the shift lever? That is located on a splined shaft. If so that is removed by removing the nut and bolts through split end of the lever and again the lever should just pull off with a bit of rocking. You might have to slightly open the slot on the end of the lever by means of a screwdriver or similar.
Re: Bsa A65 kick lever removal. Help
[Re: Dave T]
#712367 10/23/1711:44 am10/23/1711:44 am
I had that exact problem of the shaft slightly mushrooming. Ten minutes with a file and it was good to go. You should not have to force the kickstarter on there. It should slide on with little to no resistance.