This should do the trick, but with out example data it might be off the mark, luckily I was at a loose end for an hour or to and pus some data together based on the sample.

DECLARE @sys_user TABLE

(UserId bigint

,FRST_NM varchar(100)

,LST_NM varchar(100)

,APROV_ID bigint)

Insert into @sys_user

Select 800000000, 'Dave', 'Smith', NULL

UNION Select 810000000, 'Michael', 'Chak',800000000

UNION Select 811000000, 'David', 'Boon',810000000

UNION Select 811100000, 'Glen','Macgrath',811000000

UNION Select 811110000, 'Alex', 'Boon',811100000

UNION Select 811111000, 'Jim', 'Foley',811111000

UNION Select 821000000,'Stephan', '',800000000

DECLARE @userid BIGINT=800000000

select * from @sys_user

;With submenu (UserId,Name,APROV_ID,lvl)

AS

(

Select UserId, FRST_NM + ' '+LST_NM as Name,APROV_ID, 0 lvl

From @sys_user

Where UserId=@UserId

Union ALL Select

su.UserId

,su.FRST_NM + ' '+su.LST_NM

,su.APROV_ID

,sm.lvl+1

From @sys_user su

Join submenu sm ON su.APROV_ID=sm.UserId

)

Select SPACE(lvl*2)+STR(UserID) + '|| '+Name,lvl

From submenu

Order by UserId

PS: I see you're a bit of a cricket fan, hope you're enjoying the T20.