Is there any way to disable clocked task from being shown in modeline? I tried searching for variables, but i couldn't find any that turns it off.
You can set the variable
org-clock-clocked-in-display. The docstring reads:
Documentation: When clocked in for a task, Org can display the current task and accumulated time in the mode line and/or frame title. Allowed values are: both displays in both mode line and frame title mode-line displays only in mode line (default) frame-title displays only in frame title nil current clock is not displayed