This is for Mac, but must be same for other OS except the location of the preferences.
The error we get when we try an unsafe DELETE operation

On the new window, uncheck the option Safe updates

Then close and reopen the connection. No need to restart the service.
Now we are going to try the DELETE again with successful results.

So what is all about this safe updates? It is not an evil thing. This is what MySql says about it.
Using the --safe-updates Option
For beginners, a useful startup option is --safe-updates (or
--i-am-a-dummy, which has the same effect). It is helpful for cases when you might have issued a DELETE FROM tbl_name statement but
forgotten the WHERE clause. Normally, such a statement deletes all
rows from the table. With --safe-updates, you can delete rows only by
specifying the key values that identify them. This helps prevent
accidents.
When you use the --safe-updates option, mysql issues the following
statement when it connects to the MySQL server:
SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;
It is safe to turn on this option while you deal with production database. Otherwise, you must be very careful not accidentally deleting important data.