diff --git a/doc/zephyr.doxyfile.in b/doc/zephyr.doxyfile.in
index b940d943220..a5ddc43cbdb 100644
--- a/doc/zephyr.doxyfile.in
+++ b/doc/zephyr.doxyfile.in
@@ -1021,13 +1021,6 @@ VERBATIM_HEADERS       = YES
 
 ALPHABETICAL_INDEX     = YES
 
-# The COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns in
-# which the alphabetical index list will be split.
-# Minimum value: 1, maximum value: 20, default value: 5.
-# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
-
-COLS_IN_ALPHA_INDEX    = 2
-
 # In case all classes in a project start with a common prefix, all classes will
 # be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
 # can be used to specify a prefix (or a list of prefixes) that should be ignored