Hi PieUK,
You would need to consider the existing legislation within Taxation of Chargeable Gains Act 1992 (“TCGA92”).
The ""loss, destruction, dissipation or extinction"" of an asset is deemed to be a disposal by S24(1) TCGA92.
Burning a token seems to fall into that description and to that extent would constitute a disposal.
Therefore, it is possible for an allowable capital loss to arise from a disposal under TCGA 1992 s 24(1)
CG13120 - Introduction and computation: occasions of charge: assets lost/destroyed/negligible value: introduction.
Whilst you state nothing is being provided in return it is also worth signposting:
CG12965 - Capital sums derived from assets: interaction of s22 and s24 TCGA92
Which commentates on interaction of s22 and s24 TCGA92.
This covers the situation where a capital sum (money or money's worth) is received as a result of the loss or destruction of an asset.
Thank you.