Remove Dates from table t-sql
This is Sql server 2008 script.i think it can be easily translated to other rdbms.

Secondly your sample data is wrong.It should be 08:43 instead of 09:43

create table #t (CalanderDateTime datetime, PtID int,EventDateTime  datetime,GapinMinutes int)
insert into #t VALUES
 ('2017-09-23 08:34',   NULL,          NULL         ,  NULL)
 ,('2017-09-23 08:35',   NULL,          NULL         ,  NULL)
 ,('2017-09-23 08:36',   NULL,          NULL         ,  NULL)
 ,('2017-09-23 08:37',    1  ,    '2017-09-23 08:30'   ,  1 )
 ,('2017-09-23 08:38',    1  ,    '2017-09-23 08:35'   ,  4 )
 ,('2017-09-23 08:39',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:40',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:41',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:42',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:43',    1  ,    '2017-09-23 09:40'   , 3  )
 ,('2017-09-23 08:44',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:45',  NULL ,         NULL          ,NULL  )
 ,('2017-09-23 08:46',  NULL ,         NULL          ,NULL  )

 ;WITH CTE as
 (
  select * 
 ,ROW_NUMBER()OVER(ORDER BY CalanderDateTime)rn
 from #t
 )
,CTE1 AS(
 select c.rn from cte c
cross apply(select rn from cte c1 
 where c1.GapinMinutes is not null and c1.GapinMinutes&gt;3 and  
 (c.rn&gt;c1.rn and c.rn&lt;(c1.rn+c1.GapinMinutes+1)) )ca
 )
 select * from cte c
 where not exists (select rn from cte1  c1 where c.rn=c1.rn)

 drop TABLE #t