Is there a way to combine if statment with filter function?

I need to filter out some rows if a condition is true.

Tried this:

if(DiffTask$TaskCue == "square1"){DiffTasks<-subset(data,-subject==10)}

Warning message:

In if (DiffTask$TaskCue == "square1") { : the condition has length > 1 and only the first element will be used