You may want to change the redo log file size or it's location online (in case you are facing space issues on the existing disk drive).
Before changing the redo logs, take a full backup.
Drop the first redo log by using the SQL command
alter database drop logfile '<path to the redo log file>';
Now create it with your preferred location or size using the command
alter database add logfile '<preferred path and name of the log file>' size <preferred size>M;
Repeat this on the rest of the redo logs. You will encounter ORA1515 error at the point when you are deleting a redo log file that is currently in use. You can wait or skip the redo log file for now and proceed later with this redo log file. You may also force log switch to let you change the current log file using the command
alter system switch logfile;