maybe take a step back and try to explain what you actually try to achieve
A Sybase database usually consists of multiple devices
- 1 or more data devices
- 1 or more log devices
If your database is growing and nearly full (default / data segment), you can add 1 or more data devices.
If your log is growing, then schedule dump transaction commands or for big transactions add a log device (or enable db option trunc log on chkpt when you're not interested in log dumps)
If you delete old data, then the space is freed and reused
There's no need to remove old devices, because these are still being used.
If you have an issue with adding more devices, increase server parameter "number of devices"