I will assume you are referring to the Seasons skin. You need to edit /etc/weewx/skins/Seasons/index.html.tmpl (or it maybe /home/weewx/skins/Seasons/index.html.tmpl depending on your WeeWX install type) and:
1. locate and delete the following lines (circa line 61):
#if $day.inTemp.has_data
<img src="daytempin.png" alt="$obs.label.inTemp" />
#end if
2.continue searching through the file and locate and delete the corresponding week, month and year lines. The 'week' lines look like:
#if $week.inTemp.has_data
<img src="weektempin.png" alt="$obs.label.inTemp" />
#end if
3. repeat steps 1 to 2 but this time for inHumidity. The 'day' inHumidity lines are:
#if $day.inHumidity.has_data
<img src="dayhumin.png" alt="$obs.label.inHumidity" />
#end if
4. save index.html.tmpl and on the next report cycle it will be regenerated without the inTemp and inHumidity plots.
Whilst index.html will no longer display the plots WeeWX will continue generating them (or attempting to generate them). If you want to stop WeeWX generating the plots you need to edit /etc/weewx/skins/Seasons/skin.conf (or /home/weewx/skins/Seasons/skin.conf) and locate the [ImageGenerator] stanza. Then under [[day_images]], [[week_images]], [[month_images]] and [[year_images]]delete the [[[xxxtempin]]] and [[[xxxhumin]]] stanzas in toto where xxx is day, week, month and year. Save skin.conf and WeeWX will no longer attempt to generate the inTemp and inHumidity plots.
Gary