alter table table_name change old_col_name new_col_name new_col_type;
Here is the example
hive> alter table test change userVisit userVisit2 STRING;
OK
Time taken: 0.26 seconds
hive> describe test;
OK
uservisit2 string
category string
uuid string
Time taken: 0.213 seconds, Fetched: 3 row(s)