If these connections and server information are obsolete and no longer needed, you need to remove rows from this table
in order to get rid of old information since there are no options in the front end menu to remove these rows of information shown under Tools | Stat/Oracle Agent Status.
Query for this table SELECT * FROM MERC_WAKE.
Now go to Tools | Oracle Agent status and look at the timestamp for all the agents that are not responding.
Make sure you delete the correct rows of data. Below is the DML statement:
DELETE FROM MERC_WAKE
Now take a look at the Tools | Stat/Oracle Agent status before you issue another delete statement.
Deleting a wrong row by mistake is not a big deal either.
If you restart the agents they should report back to MERC_WAKE table and get displayed under Tools > Stat/Oracle Agent Status.
For Oracle Application agent the SD_CD in MERC_WAKE is displayed as a number.
So the best way to locate the entry that you want to remove is to look at the Last Time awake of the agent in Tools | Oracle Agent Status and try to match it against UPDATE_DT field in MERC_WAKE table.