如何从R上的数据框中删除特定行

Basically I have a data frame with 4 columns and several rows (now it is not important how many exactly). The last column of the data frame is an index that ranges from 0 to 99. For first (50 * 1991) rows that index is 0, for the others (50 * 1991) rows the index is 1..e so on until to 99. I would like to modify my data frame, so that the first 550 (50 * 11) rows were eliminated each time the index in the fourth column changes. Hence, it would eliminate the first 550 rows when the index is 0..the first 550 rows when the index is 1..è so on up to 99. How could I do?Basically I have a data frame with 4 columns an