diff --git a/src/extensions/rcsb/validation-report/behavior.ts b/src/extensions/rcsb/validation-report/behavior.ts
index 00b9d38fce2fb3be8dc3ea11441340be88c38aa6..cf1d189eacb130b9955908016fc8987283344e85 100644
--- a/src/extensions/rcsb/validation-report/behavior.ts
+++ b/src/extensions/rcsb/validation-report/behavior.ts
@@ -71,8 +71,7 @@ export const RCSBValidationReport = PluginBehavior.create<{ autoAttach: boolean,
         }
 
         unregister() {
-            // TODO
-            // DefaultQueryRuntimeTable.removeCustomProp(this.provider.descriptor);
+            DefaultQueryRuntimeTable.removeCustomProp(this.provider.descriptor);
 
             this.ctx.customStructureProperties.unregister(this.provider.descriptor.name);
 
diff --git a/src/mol-plugin/behavior/dynamic/custom-props/computed/accessible-surface-area.ts b/src/mol-plugin/behavior/dynamic/custom-props/computed/accessible-surface-area.ts
index 06bc52745878f8666464f6e914d00c5d1d5a0207..6d6be15f83c89ef48ecd885a375c037adbf9811a 100644
--- a/src/mol-plugin/behavior/dynamic/custom-props/computed/accessible-surface-area.ts
+++ b/src/mol-plugin/behavior/dynamic/custom-props/computed/accessible-surface-area.ts
@@ -51,8 +51,7 @@ export const AccessibleSurfaceArea = PluginBehavior.create<{ autoAttach: boolean
         }
 
         unregister() {
-            // TODO
-            // DefaultQueryRuntimeTable.removeCustomProp(this.provider.descriptor);
+            DefaultQueryRuntimeTable.removeCustomProp(this.provider.descriptor);
 
             this.ctx.customStructureProperties.unregister(this.provider.descriptor.name);
             this.ctx.representation.structure.themes.colorThemeRegistry.remove(AccessibleSurfaceAreaColorThemeProvider);
diff --git a/src/mol-script/runtime/query/base.ts b/src/mol-script/runtime/query/base.ts
index b9982624de919880b9ede41c136eebfd3381e329..dabc80ad3deb1efa464997beb2d6dc91ab8e8a92 100644
--- a/src/mol-script/runtime/query/base.ts
+++ b/src/mol-script/runtime/query/base.ts
@@ -11,9 +11,13 @@ import { MSymbol } from '../../language/symbol';
 export class QueryRuntimeTable {
     private map = new Map<string, QuerySymbolRuntime>();
 
+    removeSymbol(runtime: QuerySymbolRuntime) {
+        this.map.delete(runtime.symbol.id);
+    }
+
     addSymbol(runtime: QuerySymbolRuntime) {
         if (this.map.has(runtime.symbol.id)) {
-            throw new Error(`Symbol '${runtime.symbol.id}' already added.`);
+            console.warn(`Symbol '${runtime.symbol.id}' already added. Call removeSymbol/removeCustomProps re-adding the symbol.`);
         }
         this.map.set(runtime.symbol.id, runtime);
     }
@@ -26,6 +30,14 @@ export class QueryRuntimeTable {
         }
     }
 
+    removeCustomProp(desc: CustomPropertyDescriptor<any>) {
+        if (!desc.symbols) return;
+
+        for (const k of Object.keys(desc.symbols)) {
+            this.removeSymbol((desc.symbols as any)[k]);
+        }
+    }
+
     getRuntime(id: string) {
         return this.map.get(id);
     }