Hi,

Try the blow code with test code as reference:

public class timesheetmanagement

{   

public String weekselection{get; set;}

public String incselection{get; set;}

Public List<Timesheet_Entry__c> tentries;

Public List<Timesheet_Entry__c> otherentries;

Public Date SelectedWeek;

 public Id oppId {get; set;}

 public timesheetmanagement()

 {

     tentries=new List<Timesheet_Entry__c>();

 }

Public void deltsheet()

{

    String rownumber = System.currentPagereference().getParameters().get('rownumber');

    Decimal rownumb = Decimal.Valueof(rownumber);

    Integer rowno = rownumb.IntValue();

    String tentryid = System.currentPagereference().getParameters().get('tentryid');

    system.debug('tentries tentryid'+tentryid);

    if (rownumber != '')

        if(tentries.size()>0)

        tentries.remove(rowno);

}

public void onloadfunction()

{

    if ( weekselection != null)

    {

        SelectedWeek = date.valueOf(weekselection); 

        system.debug('The Selected Week is'+SelectedWeek);

        tentries = [select Id,Project__c,Displayfields__c,Tasks_for_Project__c,Effort__c,Week_Start_Date__c,Mon__c,Project_Task__c from Timesheet_Entry__c where Week_Start_Date__c=:SelectedWeek and Project__c!=NULL and OwnerId=:Userinfo.getUserId()];

        otherentries = [select Comments__c,Displayfields__c,Tasks_Other__c,Effort__c,Week_Start_Date__c,Mon__c,Project_Task__c from Timesheet_Entry__c where Week_Start_Date__c=:SelectedWeek and Project__c=NULL and OwnerId=:Userinfo.getUserId()];

    }

}

// Test Method

public static testMethod void CoverConstructor()

{

        Timesheet_Entry__c t=new Timesheet_Entry__c(name='dummy1',Week_Start_Date__c=date.valueof('2012-3-12'));

        insert t;

        Test.setCurrentPage(Page.vf_timesheetmanagement);

        ApexPages.currentPage().getParameters().put('rownumber','5');

        ApexPages.currentPage().getParameters().put('tentryid','fve');

        timesheetmanagement tms=new timesheetmanagement();

        tms.weekselection='2012-3-12';

        tms.deltsheet();

        tms.onloadfunction();

}

}

Did this answer your question? If not, let me know what didn't work, or if so, please mark it solved.