Delete entire rows from a table when specific column has a null after filtering

[nezuko_kamado]

How can I delete entire rows when the most important column got a null after filtered?

For example, before filtered , fourth column shows all project of {a,b,c}.

After I select Project = 'a', I would like to remove the bottom two rows that do not have selected factor(which is 'a 'here) from the table.

test data is as below

test:
load ActionDate, if ( isnull(Project ),'Unknown', Project) as Project , Approval
Inline [ ActionDate, Project , Approval
2/4/2021, a , cancel
2/4/2021, b, approve
2/4/2021, c, approve
2/5/2021, b, cancel
2/5/2021, a, approve
2/5/2021,c,approve
2/8/2021, c, approve
2/10/2021, a, approve
2/10/2021, b, cancel
2/10/2021, c, approve
3/15/2021,a, approve
3/15/2021, c, cancel
3/16/2021, c, cancel
];

[NitinK7]

try once to uncheck below box from property panel

[nezuko_kamado]

The values are NOT NULL values,  but they become displayed as  empty cells because of not having the selected value of 'a'.

'Include Null value' used when rows or columns of  original data table are blank. If this is the matter of clicking 'Include Null', I wouldn't post this question here.