How to delete a slot of an element in a list in R with lappy

So i have a long list of objects that each have a slot that i want to delete. Specifically they are storing the data in a duplicate manner. But the reason why shouldn't matter.

My main question regards what is "proper" way of doing this. So here is the set up:

q <- list()
q$useless <- rnorm(100)
q$useful <- rnorm(100)

SampleList <- list(q,q,q)

So I have a list of identical objects(or at least identical look objects). I want to delete the useless slot. why, because it is useless to me.

I can do with a loop:

for (i in 1:length(SampleList)){
   SampleList[[i]]$useless <- NULL
}

But why doesn't the lapply() version work. So guess the question is what do I not get about lapply.

lapply(SampleList, function(x){print(x$useless) })
SampleList<- lapply(SampleList, function(x){x$useless <- NULL }) #NO WORK