:~ ${HOSTNAME}$ cd Library/Application\ Support/Skype/${USERNAME}/
sqlite3 main.db
sqlite> select * from messages
sqlite> delete from messages where id > 2904;
sqlite> .exit
Edit Skype main.db for pending messages and delete them
:~ ${HOSTNAME}$ cd Library/Application\ Support/Skype/${USERNAME}/
sqlite3 main.db
sqlite> select * from messages
sqlite> delete from messages where id > 2904;
sqlite> .exit