The way i envision this is by adding a delete button next to every value in the 'latest values' list of a single item ( through Monitoring -> latest data -> Value X -> Graph -> Values ). That would make it so much easier to delete inappropriate single values.

Users time to time have this problem, just a confirmation:
https://www.zabbix.com/forum/showthread.php?p=126654

This feature would be awesome to have and probably not that hard to implement.

Any news about this issue?

I'm still waiting for this feature, too. Would be really cool instead of always manually querying the database.

I also need this feature, there is an undesirable traffic value of 27 Tbits which I want to erase from the history. Is there any problem in deleting this amount directly from the database?

I once wrote a short tutorial for myself:

1. Get itemid from graph URL (for example: /history.php?action=showgraph&itemids[]=444871)
2. Access Zabbix database.
3. Find out which type your item has (uint, text, str, log) to know in which history table you have to search for:
   • history_uint
   • history_text
   • history_str
   • history_log
4. Search the appropriate table with the itemid for the spike:

   zabbix=# select * from history_uint where itemid=444871 order by value DESC limit 5;
    itemid |   clock    |     value      |    ns
   --------+------------+----------------+-----------
    444871 | 1543993500 | 29729269162576 | 606002333
    444871 | 1543964400 |    32170824376 | 384896023
    444871 | 1543965000 |    30664167112 | 514850665
    444871 | 1543964700 |    29971309024 | 862951334
    444871 | 1543965300 |    26845634240 | 455393174
   (5 rows)
   

5. Simply remove the obviously wrong value from the table:

   zabbix=# delete from history_uint where itemid=444871 and clock=1543993500 and value=29729269162576;
   DELETE 1