How to shrink "permanent" tablespace?
The error message is quite straightforward. You are trying to shrink a permanent tablespace using a command to shrink temporary tablespace. 


12916, 00000, "cannot shrink permanent or dictionary managed tablespace"
// *Cause: An attempt was made to shrink a permanent tablespace or a
//         dictionary managed tablespace.
// *Action: Check the tablespace type and issue the statement only on
//          locally managed temporary tablespaces.



Example to resize BIGFILE Tablespace.

ALTER TABLESPACE bigtbs RESIZE 80G;


Refer to Altering and Maintaining Tablespaces