You shouldn't drop any seeded/Oracle Standard objects of any EBS Product whether you use them or not.
To reclaim space, start at finding the largest objects 1st. There are several Purge Concurrent Programs which you can use as well. If there are any other large tables, then take a call wisely based on the business.
Looks like the error it is showing is about FND_LOBS. Check from DBA_LOBS with that LOB name given whats the table name. You can purge FND_LOBS attachments.
Just to add: Using advanced compression is one of the best options. Though you will need to buy additional license, you can achieve 40-70% compression and also it will control the future growth rate by almost the same %.
Following is the dba_lobs table information. How to purge fnd_lobs attachments? Is this correct way to purge the fnd_lobs attachments?
OWNER TABLE_NAME COLUMN_NAME SEGMENT_NAME TABLESPACE_NAME INDEX_NAME CHUNK PCTVERSION RETENTION FREEPOOLS CACHE LOGGING ENCRYPT COMPRESSION DEDUPLICATION IN_ROW FORMAT PARTITIONED SECUREFILE SEGMENT_CREATED RETENTION_TYPE RETENTION_VALUE APPS AW$ODPCODE AWLOB SYS_LOB0000137260C00004$$ SYSTEM SYS_IL0000137260C00004$$ 8192 0 1 YES NONE NONE NONE NONE NO NOT APPLICABLE YES NO N/A NO APPS AW$BSC_AW AWLOB SYS_LOB0000137319C00004$$ SYSTEM SYS_IL0000137319C00004$$ 8192 0 1 YES NONE NONE NONE NONE NO NOT APPLICABLE YES NO N/A NO FPA AW$FPAPJP AWLOB SYS_LOB0000137437C00004$$ APPS_TS_TX_DATA SYS_IL0000137437C00004$$ 8192 10 1 YES NONE NO NO NO NO NOT APPLICABLE YES YES N/A DEFAULT APPS AW$XWDEVKIT_BACKUP AWLOB SYS_LOB0000524029C00004$$ APPS_TS_TX_DATA SYS_IL0000524029C00004$$ 8192 10 1 YES NONE NO NO NO NO NOT APPLICABLE YES YES N/A DEFAULT APPS AW$XWDEVKIT AWLOB SYS_LOB0000757779C00004$$ APPS_TS_TX_DATA SYS_IL0000757779C00004$$ 8192 10 1 YES NONE NO NO NO NO NOT APPLICABLE YES YES N/A DEFAULT
You cannot simply purge data from fnd_lobs table. Please have a look at this blog post for more information on the issue: