Haven't seen this before. One thing you can try is to upload the plugin to the server, unpack it, and put the file back in the ow_plugins folder. You may even have to restore the database from a backup. Go back to your admin panel and try to activate the plugin.

Typically to delete a plugin you would do the following in the admin panel.
1. If it is already active, hover over it, and click uninstall.
2. If it is deactivated. Activate it, and hover over it, and click uninstall.
3. Go to available plugins list. Hover over it, and click delete.
The files in the plugin would take care of the rest "i.e. Install, deactivate, uninstall files"

uninstall is not working showing uninstall in progress but not working 

Try to clear your browser cache

Try to run www.yoursite.com/ow_cron/run.php

From what folder and table in the database did you delete the forum files and record?

i have deleted ox_forum folders from database now when i activate plugin showing error database ow_forum_topic not exits i have uploaded forum plugin again but not creating table in the database 

you should delete forum plugin in ow_base_plugin

delete forum folder in ow_plugins folder

then check if the forum plugin is deleted in the admin

then you can try to upload the file back. 

Why do you upload the plugin again, if you wanted to uninstall it in the first place?

there is no any forum item in ow_base_plugin 

i uninstalled it by mistake but now its not uninstalling and not working 

i got it thankx for your help not showing forum plugin in the inactive plugins list should i upload plugin again to install it 

check this manual now: https://docs.oxwall.org/install:plugin