  We investigate the spin interaction and the gravitational radiation thermally
allowed in a head-on collision of two rotating Hayward black holes. The Hayward
black hole is a regular black hole in a modified Einstein equation, and hence
it can be an appropriate model to describe the extent to which the regularity
effect in the near-horizon region affects the interaction and the radiation. If
one black hole is assumed to be considerably smaller than the other, the
potential of the spin interaction can be analytically obtained and is dependent
on the alignment of angular momenta of the black holes. For the collision of
massive black holes, the gravitational radiation is numerically obtained as the
upper bound by using the laws of thermodynamics. The effect of the Hayward
black hole tends to increase the radiation energy, but we can limit the effect
by comparing the radiation energy with the gravitational waves GW150914 and
GW151226.
