Base R: change already existing title's font size and label

[learning_R]

This is probably basic, but given this code how can I 1) increase the title font size and 2) remove the label lm(mpg ~ wt)?

d <- mtcars
fit <- lm(mpg ~ wt, data = d) # fit the model
d$predicted <- predict(fit)   # Save the predicted values
d$residuals <- residuals(fit) # Save the residual values

p<-plot(fit, which=2, col=c("red")# Q-Q Plot

I tried

p<-plot(fit, which=2, col=c("red"),main="Normal Q-Q",cex.main=5,xlab="My label")  

but this 1) writes a second title, on top of the already existing one (which I don't know how to remove) and 2) changes only the first part of the label, leaving lm(mpg ~ wt).

[FJCC]

This seems to work, though there may be a better method.

p<-plot(fit, which=2, col=c("red"), caption="", main="Normal Q-Q", sub.caption="",
        cex.main=5, xlab="My label")