After Bromley finished their Blue Square South season with a 1-0 home defeat by Dorchester on Saturday they signed off in 11th-place.
Osborn's assistant Bowry told nonleaguedaily.com: "It is true myself and Simon are leaving.
"We have been told by the chairman that the club is up for sale and this did not really say to me that they wanted me to stay."
Bromley chairman Jeremy Dolke has put the club up for sale on April 15th and has since stepped down from his role.
He took over as majority shareholder in 2001, with the club languishing near the bottom of the Ryman Division One but before his departure the club website: "The club has now reached a crossroads and in order for it to move on to the next level significant investment is needed.
"I don't have the financial resources or the energy needed.
Recent form under Osborn has seen the side just about win more than lose.
February 2008 | ||||||
02/02/08 | League | Sutton United | (H) | W1-0 | 648 | Details |
05/02/08 | LSCqf | AFC Wimbledon | (H) | W4-1 | 512 | Details |
09/02/08 | League | Hayes & Yeading | (A) | L1-6 | 295 | Details |
16/02/08 | League | Weston-super-Mare | (H) | W3-1 | 514 | Details |
23/02/08 | League | Basingstoke Town | (A) | D1-1 | 445 | Details |
26/02/08 | KSCsf | Cray Wanderers | (A) | L1-6 | 535 | Details |
March 2008 | ||||||
01/03/08 | League | Braintree Town | (H) | W4-0 | 564 | Details |
08/03/08 | League | Welling United | (H) | W2-0 | 761 | Details |
11/03/08 | LSCsf | Hendon | (H) | L0-2 | 232 | Details |
15/03/08 | League | Bishop's Stortford | (A) | L0-2 | 514 | Details |
22/03/08 | League | Eastbourne Borough | (A) | W2-1 | 1132 | Details |
24/03/08 | League | Cambridge City | (H) | W3-1 | 637 | Details |
29/03/08 | League | Hampton & Richmond | (H) | L0-2 | 657 | Details |
April 2008 | ||||||
05/04/08 | League | Newport County | (A) | L1-3 | 1057 | Details |
12/04/08 | League | Havant & Waterlooville | (H) | W2-1 | 603 | Details |
19/04/08 | League | Weston-super-Mare | (A) | W1-0 | 323 | Details |
26/04/08 | League | Dorchester Town | (H) | L0-1 | 801 | Details |