Please help me to resolve the error which i am trying to submit the content in Alfresco.
Also help me to clear the list in My Task to do panel.
The error is likely due to custom workflow development (your other question indicated via the screenshot that the affected tasks / workflows are not related to default out-of-the-box workflows). For that reason it is hard to say what can solve / work around this issue. I can't even guarantee that you can submit these items even if the existing workflows / tasks have been completed.
You will have to provide details as much as possible related to your problem. Chances of getting quick resolution goes up dramatically if you do so. Please provide more detail on your problem. Where you are trying to submit? How? Screenshot will make things more clear.
To remove tasks from to do dashlet you will have take action on those tasks which are waiting for your inputs.
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