Remove Guideline 9b+ (#1242)

Co-authored-by: OJCubing <[email protected]>

wca-guidelines.md

@@ -123,7 +123,6 @@ To be more informative, each Guideline is classified using one of the following
 
 ## <article-9><events><events> Article 9: Events
 
-- 9b+) [ADDITION] For an event with multiple rounds, every round after the first round (especially the final round) should be "Average of 5" or "Mean of 3" if one of these is a valid format.
 - 9b++) [ADDITION] Events other than those specified in [Regulation 9b](regulations:regulation:9b) may be held during a competition, but will be considered unofficial and therefore will not be included in the official results of the competition.
 - 9b3b+) [CLARIFICATION] The "Mean of 3" statistic does not affect the competitor's ranking in a "Best of 3" round (which is based on the best result). The WCA recognizes it outside of the competition format.
 - 9f1+) [EXAMPLE] If the timer displays 12.678 for an attempt, the original recorded time is 12.67 (drop any digit after a hundredth of a second). A judge may write the full-precision time on the score sheet (and keep the precision in the calculation of penalties), as long as the score taker truncates it for the official results.