When the 'Troubles' started in 1969 I and a Hell of a lot of other UK singers dropped the Rebel songs from our rep. There seemed to be remarkably little point in singing 'Dublin In The Green',cracking chorus tho it was when there coud be people in the audience with Husbands, brothers etc serving in Northern Ireland.
That is the only time I have consciously dropped a complete Genre of songs all at once. The rest of the time , a lot of Older songs have just been displaced by more recently learned material.