mydf <- data.frame(a = 1:5, 
                   b = 6:10,
                   c = 11:15)
mydf

结果:

a b c
1 1 6 11
2 2 7 12
3 3 8 13
4 4 9 14
5 5 10 15

删除变量"c":

mydf['c'] <- NULL
mydf

结果:

a b
1 1 6
2 2 7
3 3 8
4 4 9
5 5 10