I got it working by making a linqDataSource with a filter made in the UI and took the filter format, here is the code:
<asp:EntityDataSource ID="TaskDataSource" runat="server" ConnectionString="name=ScheduleEntities" DefaultContainerName="ScheduleEntities" EnableFlattening="False" EntitySetName="TaskItems" EnableInsert="True" EnableUpdate="True" OrderBy="" Where="deleted == @deleted">
<WhereParameters>
<asp:Parameter DefaultValue="False" Name="deleted" Type="Boolean" />
</WhereParameters>
</asp:EntityDataSource>
BUT, I couldn't end up using this because I needed to use the dynamic filters on the grid also, so my workaround was to hide rows during the binding process(if there is a more efficient way please update me!) with this:
protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
{
var editItem = e.Item as GridEditFormItem;
if (e.Item is GridDataItem && !e.Item.IsInEditMode)
{
GridDataItem item = (GridDataItem)e.Item;
bool success,deleted;
bool.TryParse(item["deleted"].Text, out success);
if (success)
{
deleted = bool.Parse(item["deleted"].Text);
if (deleted)
{
item.Display = false;
}
}
}
}